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Sources & methodology

How we decide what is an error, what counts as evidence, and every source cited on the site — 255 in total.

Updated

Our sourcing rules#

  1. Primary first. For HTTP behavior we cite the RFC, not a blog post about the RFC. For a historical software failure we cite the official investigation board or regulator. For nutrition and money we cite the agency that issues the guidance (for example the FDA, USDA or CFPB) or the original peer-reviewed paper.
  2. Numbers come with a source and a date. If a statistic appears on erroneo.us, it links to the place it was published, stated as that source states it.
  3. No invented examples dressed as facts. Example sentences and code samples are written by us to illustrate a point; they are never presented as quotations.
  4. Usage questions get the honest answer. Dictionaries describe how people use words, while style guides prescribe. When the two diverge, we show both.
  5. Contested science is labeled. When a famous finding has failed to replicate or has been seriously critiqued, we say so.

Kinds of sources we use#

TopicPreferred sources
English usageMerriam-Webster, Cambridge and Oxford dictionaries; established style and writing guides
HTTPIETF RFCs (RFC 9110 and related), MDN, Google Search Central for SEO behavior
Language errorsMDN JavaScript reference, docs.python.org
Software failuresInquiry board reports, NASA, ESA, GAO, SEC, vendor root-cause analyses
Psychology & logicOriginal papers, replication studies, Stanford and Internet Encyclopedias of Philosophy
Science & historyNASA, NOAA, Smithsonian, Library of Congress, Britannica, peer-reviewed papers
NutritionFDA, USDA, NIH, CDC, Dietary Guidelines for Americans, peer-reviewed research
MoneyCFPB, FTC, SEC/Investor.gov, Federal Reserve

Freshness#

Every page carries an “Updated” stamp. The whole site was reviewed in October 2026, and every link is re-checked with our link checker before each release. If you find a dead link or an outdated claim, see the corrections policy.

Full bibliography#

Every source cited on erroneo.us, grouped by the page that cites it.

Commonly confused words 17 sources

Cited on Commonly confused words

  1. Cambridge Dictionary, English Grammar Today: Affect or effect?
  2. American Heritage Dictionary: usage note at 'affect'
  3. Cambridge Dictionary: There, their or they're?
  4. Cambridge Dictionary: It's or its?
  5. American Heritage Dictionary: usage note at 'then'
  6. American Heritage Dictionary: usage note at 'complement'
  7. American Heritage Dictionary: usage note at 'principal'
  8. Cambridge Dictionary: Principal or principle?
  9. American Heritage Dictionary: usage note at 'less'
  10. Cambridge Dictionary: Less or fewer?
  11. American Heritage Dictionary: usage note at 'infer'
  12. Cambridge Dictionary: Imply or infer?
  13. Cambridge Dictionary: Advice or advise?
  14. Cambridge Dictionary: Farther, farthest or further, furthest?
  15. Cambridge Dictionary: Altogether or all together?
  16. Cambridge Dictionary: Maybe or may be?
  17. American Heritage Dictionary: usage note at 'comprise'
Common grammar mistakes 17 sources

Cited on Common grammar mistakes

  1. Harvard Law School Writing Center: Common language errors
  2. Purdue OWL: Apostrophe introduction
  3. Purdue OWL: Dangling modifiers and how to correct them
  4. Cambridge Dictionary: It's or its?
  5. Wikipedia: Hypercorrection
  6. VOA Learning English: Wordmaster on hypercorrection
  7. American Heritage Dictionary: usage note at 'who'
  8. Cambridge Dictionary: Who, whom
  9. American Heritage Dictionary: usage note at 'lay'
  10. Cambridge Dictionary: Lay or lie?
  11. American Heritage Dictionary: usage note at 'less'
  12. Wikipedia: Stress and vowel reduction in English (weak forms)
  13. Geoffrey K. Pullum: Stranded prepositions
  14. The New Republic: The dangling preposition myth
  15. Wikipedia: Split infinitive
  16. American Heritage Dictionary: usage note at 'data'
  17. American Heritage Dictionary: usage note at 'hopefully'
Commonly misspelled words 6 sources

Cited on Commonly misspelled words

  1. Learning English with Oxford (OUP): 20 commonly misspelt words in English
  2. Washingtonian: Google's 2019 most-searched 'how to spell' words by state
  3. Wikipedia: I before E except after C
  4. Wikipedia: Commonly misspelled English words
  5. Dictionary.com: mischievous
  6. Wikipedia: English orthography
Commonly mispronounced words 16 sources

Cited on Commonly mispronounced words

  1. American Heritage Dictionary: usage note at 'nuclear'
  2. Wikipedia: Nucular
  3. American Heritage Dictionary: usage note at 'February'
  4. Wikipedia: Dissimilation
  5. American Heritage Dictionary: usage note at 'often'
  6. Wikipedia: Spelling pronunciation
  7. American Heritage Dictionary: 'ax' (Our Living Language note)
  8. American Heritage Dictionary: usage note at 'height'
  9. American Heritage Dictionary: usage note at 'forte'
  10. American Heritage Dictionary: usage note at 'comptroller'
  11. American Heritage Dictionary: 'Arctic'
  12. American Heritage Dictionary: 'sherbet'
  13. Dictionary.com: espresso
  14. Dictionary.com: mischievous
  15. American Heritage Dictionary: usage note at 'nauseous'
  16. Wikipedia: GIF (Pronunciation)
Misused idioms and phrases 19 sources

Cited on Misused idioms and phrases

  1. The Phrase Finder: For all intents and purposes
  2. Grammarly: For all intents and purposes
  3. Wikipedia: Eggcorn
  4. Grammarphobia: More about caring less
  5. Merriam-Webster: Is it 'could' or 'couldn't care less'?
  6. American Heritage Dictionary: usage note at 'beg'
  7. Wikipedia: Begging the question
  8. American Heritage Dictionary: usage note at 'irregardless'
  9. Grammarphobia: Literal minded
  10. Merriam-Webster: Did we change the definition of 'literally'?
  11. The Phrase Finder: Nip in the bud
  12. The Phrase Finder: Toe the line
  13. Vocabulary.com: Case in point vs case and point
  14. American Heritage Dictionary: usage note at 'hone'
  15. American Heritage Dictionary: usage note at 'chomp'
  16. American Heritage Dictionary: usage note at 'moot'
  17. American Heritage Dictionary: usage note at 'decimate'
  18. American Heritage Dictionary: usage note at 'ironic'
  19. American Heritage Dictionary: usage note at 'peruse'
HTTP status codes, explained properly 13 sources

Cited on HTTP status codes, explained properly

  1. RFC 9110: HTTP Semantics, Section 15 (Status Codes)
  2. IANA HTTP Status Code Registry
  3. RFC 6585: Additional HTTP Status Codes (428, 429, 431, 511)
  4. RFC 7725: An HTTP Status Code to Report Legal Obstacles (451)
  5. RFC 8297: An HTTP Status Code for Indicating Hints (103)
  6. RFC 8470: Using Early Data in HTTP (425)
  7. RFC 4918: HTTP Extensions for WebDAV (207, 423, 424, 507)
  8. RFC 2324: Hyper Text Coffee Pot Control Protocol (418)
  9. RFC 9457: Problem Details for HTTP APIs
  10. MDN: HTTP response status codes
  11. Google Search Central: How HTTP status codes affect Google Search
  12. Cloudflare: Cloudflare 5xx errors
  13. nginx source: ngx_http_request.h (499 definition)
401 Unauthorized vs 403 Forbidden 10 sources

Cited on 401 Unauthorized vs 403 Forbidden

  1. RFC 9110 §15.5.2: 401 Unauthorized
  2. RFC 9110 §15.5.4: 403 Forbidden
  3. RFC 9110 §11.6.1: WWW-Authenticate
  4. RFC 6750: OAuth 2.0 Bearer Token Usage, §3.1 Error Codes
  5. MDN: 403 Forbidden
  6. MDN: 401 Unauthorized
  7. GitHub Docs: Troubleshooting the REST API
  8. Google Search Central: How HTTP status codes affect Google Search
  9. RFC 9457: Problem Details for HTTP APIs
  10. Django documentation: Cross Site Request Forgery protection
404 Not Found 8 sources

Cited on 404 Not Found

  1. RFC 9110 §15.5.5: 404 Not Found
  2. RFC 9110 §15.5.11: 410 Gone
  3. RFC 9110 §15.5.4: 403 Forbidden (hiding a resource with 404)
  4. Google Search Central: How HTTP status codes affect Google Search
  5. Google Search Central: Troubleshoot crawling errors (soft 404s)
  6. MDN: 404 Not Found
  7. GitHub Docs: Troubleshooting the REST API
  8. nginx: ngx_http_core_module (try_files, error_page)
429 Too Many Requests 10 sources

Cited on 429 Too Many Requests

  1. RFC 6585 §4: 429 Too Many Requests
  2. RFC 6585 §7.2: Security considerations for 429
  3. RFC 9110 §10.2.3: Retry-After
  4. IETF draft-ietf-httpapi-ratelimit-headers
  5. Marc Brooker, Exponential Backoff And Jitter (AWS Architecture Blog)
  6. nginx: ngx_http_limit_req_module
  7. Google Search Central: How HTTP status codes affect Google Search
  8. GitHub Docs: Troubleshooting the REST API (rate limits)
  9. MDN: 429 Too Many Requests
  10. Google SRE Book: Handling Overload
500 Internal Server Error 8 sources

Cited on 500 Internal Server Error

  1. RFC 9110 §15.6.1: 500 Internal Server Error
  2. RFC 9110 §15.6: Server Error 5xx
  3. OWASP Error Handling Cheat Sheet
  4. OWASP: Improper Error Handling
  5. RFC 9457: Problem Details for HTTP APIs
  6. Google Search Central: How HTTP status codes affect Google Search
  7. Google Search Central: Troubleshoot crawling errors
  8. MDN: 500 Internal Server Error
502 Bad Gateway vs 504 Gateway Timeout (and 503) 12 sources

Cited on 502 Bad Gateway vs 504 Gateway Timeout (and 503)

  1. RFC 9110 §15.6.3: 502 Bad Gateway
  2. RFC 9110 §15.6.4: 503 Service Unavailable
  3. RFC 9110 §15.6.5: 504 Gateway Timeout
  4. RFC 9110 §10.2.3: Retry-After
  5. nginx: ngx_http_proxy_module (timeouts)
  6. Caddy: reverse_proxy directive
  7. AWS: Troubleshoot your Application Load Balancers
  8. Cloudflare: Error 524
  9. Cloudflare: Cloudflare 5xx errors
  10. Google Search Central: Pause or disable a website
  11. Google Search Central: How to deal with planned site downtime (2011)
  12. Google SRE Book: Addressing Cascading Failures
418 I'm a teapot 5 sources

Cited on 418 I’m a teapot, explained

  1. RFC 2324: Hyper Text Coffee Pot Control Protocol (HTCPCP/1.0)
  2. RFC 7168: HTCPCP for Tea Efflux Appliances (HTCPCP-TEA)
  3. RFC 9110: HTTP Semantics, Section 15.5.19 (418 Unused)
  4. RFC 9110: HTTP Semantics, Section 15 (Status Codes)
  5. IANA HTTP Status Code Registry
Common JavaScript errors, explained 14 sources

Cited on Common JavaScript errors, explained

  1. MDN: JavaScript error reference
  2. MDN: TypeError: "x" is undefined / can't access property
  3. MDN: TypeError: "x" is not a function
  4. MDN: ReferenceError: "x" is not defined
  5. MDN: SyntaxError: unexpected token
  6. MDN: SyntaxError: JSON.parse: bad parsing
  7. MDN: InternalError: too much recursion
  8. MDN: TypeError: invalid assignment to const
  9. MDN: ReferenceError: can't access lexical declaration before initialization
  10. MDN: Window: unhandledrejection event
  11. MDN: CORS errors
  12. MDN: Reason: CORS header 'Access-Control-Allow-Origin' missing
  13. MDN: Optional chaining (?.)
  14. Node.js CLI docs: --unhandled-rejections
Common Python errors, explained 8 sources

Cited on Common Python errors, explained

  1. Python docs: Built-in Exceptions
  2. Python docs: What's New in Python 3.10 (Better error messages)
  3. Python docs: What's New in Python 3.12 (Improved error messages)
  4. PEP 657: Include Fine Grained Error Locations in Tracebacks
  5. PEP 8: Indentation
  6. Python FAQ: Why am I getting an UnboundLocalError?
  7. Python docs: sys.getrecursionlimit
  8. Python docs: Installing Python Modules
Famous software bugs in history 14 sources

Cited on Famous software bugs in history

  1. ARIANE 5 Flight 501 Failure: Report by the Inquiry Board (1996), text mirror at University of Minnesota
  2. NASA: Mars Climate Orbiter Mishap Investigation Board Phase I Report (10 November 1999)
  3. Leveson & Turner, An Investigation of the Therac-25 Accidents, IEEE Computer, 1993 (course copy, Michigan State University)
  4. U.S. SEC press release 2013-222: SEC Charges Knight Capital With Violations of Market Access Rule
  5. U.S. SEC Order, In the Matter of Knight Capital Americas LLC, Release No. 34-70694
  6. GAO/IMTEC-92-26: Patriot Missile Defense: Software Problem Led to System Failure at Dhahran, Saudi Arabia
  7. Douglas N. Arnold (University of Minnesota): The Patriot Missile Failure
  8. Earlham College CS: Bugs in the Intel Microprocessors (Pentium FDIV)
  9. U.S.-Canada Power System Outage Task Force: Final Report on the August 14, 2003 Blackout
  10. CrowdStrike: Falcon Update for Windows Hosts, Technical Details
  11. CrowdStrike: Channel File 291 Incident Root Cause Analysis (6 August 2024)
  12. Microsoft: Helping our customers through the CrowdStrike outage (20 July 2024)
  13. Wikipedia: Year 2000 problem
  14. glibc wiki: Y2038 Proofness Design
Cognitive biases: the predictable ways good minds go wrong 26 sources

Cited on Cognitive biases: the predictable ways good minds go wrong

  1. Tversky & Kahneman (1974), Judgment under Uncertainty: Heuristics and Biases, Science
  2. Tversky & Kahneman (1973), Availability: A heuristic for judging frequency and probability, Cognitive Psychology
  3. Kahneman & Tversky (1973), On the psychology of prediction, Psychological Review
  4. Tversky & Kahneman (1981), The Framing of Decisions and the Psychology of Choice, Science
  5. Kahneman & Tversky (1979), Prospect Theory, Econometrica
  6. Nickerson (1998), Confirmation Bias: A Ubiquitous Phenomenon in Many Guises, Review of General Psychology
  7. Kruger & Dunning (1999), Unskilled and unaware of it, Journal of Personality and Social Psychology
  8. Magnus & Peresetsky (2022), A Statistical Explanation of the Dunning-Kruger Effect, Frontiers in Psychology
  9. McGill Office for Science and Society, The Dunning-Kruger Effect Is Probably Not Real
  10. Arkes & Blumer (1985), The psychology of sunk cost, Organizational Behavior and Human Decision Processes
  11. Mangel & Samaniego (1984), Abraham Wald's Work on Aircraft Survivability, JASA
  12. Fischhoff (1975), Hindsight is not equal to foresight, Journal of Experimental Psychology: Human Perception and Performance
  13. Buehler, Griffin & Ross (1994), Exploring the planning fallacy, JPSP
  14. Nisbett & Wilson (1977), The halo effect, JPSP
  15. Ross (1977), The Intuitive Psychologist and His Shortcomings, Advances in Experimental Social Psychology
  16. Pronin, Lin & Ross (2002), The Bias Blind Spot, Personality and Social Psychology Bulletin
  17. Samuelson & Zeckhauser (1988), Status quo bias in decision making, Journal of Risk and Uncertainty
  18. Tversky & Kahneman (1971), Belief in the law of small numbers, Psychological Bulletin
  19. Sharot (2011), The optimism bias, Current Biology
  20. Norton, Mochon & Ariely (2012), The IKEA effect, Journal of Consumer Psychology
  21. Iyengar & Lepper (2000), When choice is demotivating, JPSP
  22. Scheibehenne, Greifeneder & Todd (2010), Can There Ever Be Too Many Options?, Journal of Consumer Research
  23. Open Science Collaboration (2015), Estimating the reproducibility of psychological science, Science
  24. Hagger et al. (2016), A Multilab Preregistered Replication of the Ego-Depletion Effect, Perspectives on Psychological Science
  25. Doyen et al. (2012), Behavioral Priming: It's All in the Mind, but Whose Mind?, PLoS ONE
  26. Klein et al. (2014), Investigating variation in replicability: A Many Labs replication project, Social Psychology
Logical fallacies: how arguments break, with examples 4 sources

Cited on Logical fallacies: how arguments break, with examples

  1. Internet Encyclopedia of Philosophy, Fallacies
  2. Stanford Encyclopedia of Philosophy, Fallacies
  3. Stanford Encyclopedia of Philosophy, Aristotle's Logic
  4. Purdue OWL, Logical Fallacies
Science myths that refuse to die 19 sources

Cited on Science myths that refuse to die

  1. Scientific American, Do People Only Use 10 Percent of Their Brains?
  2. Scientific American (2008), Is China's Great Wall Visible from Space?
  3. Gee, Stephenson & Wright (1994), Temporal discrimination learning of operant feeding in goldfish, JEAB
  4. Jacobs, Deegan & Neitz (1998), Photopigment basis for dichromatic color vision in cows, goats, and sheep, Visual Neuroscience
  5. National Weather Service, Lightning Myths
  6. Spence (2022), The tongue map and the spatial modulation of taste perception, Current Research in Food Science
  7. Chandrashekar et al. (2006), The receptors and cells for mammalian taste, Nature
  8. Tuthill & Azim (2018), Proprioception, Current Biology
  9. Unger (1998), Does knuckle cracking lead to arthritis of the fingers?, Arthritis & Rheumatism (PubMed)
  10. Swezey & Swezey (1975), The consequences of habitual knuckle cracking, Western Journal of Medicine (PubMed)
  11. deWeber, Olszewski & Ortolano (2011), Knuckle cracking and hand osteoarthritis, JABFM
  12. Rizvi et al. (2018), Review of the clinical anatomy of knuckle cracking, Clinical Anatomy (PubMed)
  13. NASA Space Place, What Causes the Seasons?
  14. Kienle et al. (1996), Why do veins appear blue? A new look at an old question, Applied Optics
  15. Stuart-Fox & Moussalli (2008), Selection for social signalling drives the evolution of chameleon colour change, PLoS Biology
  16. Teyssier et al. (2015), Photonic crystals cause active colour change in chameleons, Nature Communications
  17. Zanotto (1998), Do cathedral glasses flow?, American Journal of Physics
  18. Burke Museum, Myth: You swallow spiders in your sleep
  19. Mental Floss, How Many Spiders Do You Really Swallow in Your Sleep?
History myths: what really happened 16 sources

Cited on History myths: what really happened

  1. History.com, Was Napoleon Short? Origins of the 'Napoleon Complex'
  2. National Museum of Denmark, Berserkers (on horned helmets)
  3. National Geographic, Facts vs fiction: the real Vikings
  4. History.com, Christopher Columbus Never Set Out to Prove the Earth Was Round
  5. TIME, Did Einstein flunk math?
  6. History.com, Did Marie-Antoinette Really Say 'Let Them Eat Cake'?
  7. Britannica, Did Marie-Antoinette Really Say 'Let Them Eat Cake'?
  8. Our World in Data, Life Expectancy
  9. Our World in Data, Mortality in the past: every second child died
  10. History.com, Were Witches Burned at the Stake During the Salem Witch Trials?
  11. Salem Witch Museum, FAQs
  12. History.com, 7 Famous Torture Devices, Real and Mythical
  13. History.com, Did Nero Really Fiddle While Rome Burned?
  14. UC Berkeley Library, Van Gogh's ear: Bancroft Library document
  15. Smithsonian National Museum of American History, Lighting A Revolution: Joseph W. Swan
  16. Smithsonian National Museum of American History, Lighting A Revolution: Thomas A. Edison
Nutrition myths: what the evidence actually says 19 sources

Cited on Nutrition myths: what the evidence actually says

  1. Dietary Guidelines for Americans, 2015–2020 (PDF, ODPHP)
  2. Dietary Guidelines for Americans, 2020–2025 (PDF)
  3. Dietary Guidelines for Americans, 2025–2030 (PDF)
  4. Harvard T.H. Chan School of Public Health, The Nutrition Source: Carbohydrates
  5. Li et al. (2017), Selected nutrient analyses of fresh, fresh-stored, and frozen fruits and vegetables, J. Food Composition and Analysis
  6. Wolraich, Wilson & White (1995), The effect of sugar on behavior or cognition in children: a meta-analysis, JAMA (PubMed)
  7. FDA: Questions and Answers on Monosodium Glutamate (MSG)
  8. NCCIH: “Detoxes” and “Cleanses”: What You Need To Know
  9. Valtin (2002), “Drink at least eight glasses of water a day.” Really?, Am J Physiol (PubMed)
  10. National Academies: Report sets dietary intake levels for water, salt and potassium (2004)
  11. America's Test Kitchen: Searing steak
  12. Harvard Health Publishing: Microwave cooking and nutrition
  13. Miranda & Schaffner (2016), Longer Contact Times Increase Cross-Contamination of Enterobacter aerogenes from Surfaces to Food, Appl Environ Microbiol (PubMed)
  14. USDA Table of Nutrient Retention Factors, Release 6 (2007) (PDF)
  15. USDA AMS Egg-Grading Manual (PDF)
  16. Harvard Health Publishing: No need to shun gluten if you don't have celiac disease, study suggests
  17. Smith-Spangler et al. (2012), Are organic foods safer or healthier than conventional alternatives?, Ann Intern Med (PubMed)
  18. Stanford Medicine News: Little evidence of health benefits from organic foods (2012)
  19. USDA FSIS: Food Product Dating
Money mistakes and personal-finance myths 12 sources

Cited on Money mistakes and personal-finance myths

  1. Federal Reserve: Economic Well-Being of U.S. Households in 2025 (executive summary)
  2. Federal Reserve SHED data: unexpected expenses table
  3. CFPB: An essential guide to building an emergency fund
  4. Federal Reserve G.19 Consumer Credit release (credit card interest rates)
  5. CFPB: What is a credit inquiry?
  6. myFICO: What's in my FICO Scores?
  7. SEC Investor.gov: Employer-Sponsored Plans
  8. SEC Investor.gov: Understanding Fees
  9. SEC Investor.gov: What is compound interest?
  10. SEC Investor.gov: Dollar Cost Averaging
  11. FTC: New FTC Data Show a Big Jump in Reported Losses to Fraud to $12.5 Billion in 2024
  12. IRS: Tax Withholding Estimator