Sources & Citation Policy

Last updated: November 12, 2026

1Lecture uses sources to support accurate explanations and help readers explore biology beyond an individual lesson. This policy sets out how references should be selected, checked, presented, and maintained across our articles, diagrams, worked examples, quizzes, and interactive materials.

It complements our Editorial Policy and Research & Science Review Standards. A citation should make the basis of an explanation easier to examine.

Choosing Appropriate Sources

We select sources according to the question being addressed. Established textbooks and authoritative educational references are useful for foundational concepts. Review articles help place findings in context, while original research is appropriate for specific results, methods, or developing questions.

University resources, scientific organizations, official databases, and technical documentation may also be useful when their content is relevant and attributable.

Sources should be evaluated for expertise, publication context, methods, limitations, and applicability. Neither a recognizable publisher nor a recent publication date removes the need to examine the material itself.

Search results, news reports, and general reference websites may help locate evidence. Important or disputed scientific claims should be traced to suitable underlying references wherever possible.

Connecting Citations to Claims

References should support the particular statements associated with them. A source that discusses a subject generally may not support a precise number, mechanism, comparison, or conclusion.

Citations should appear close enough to the relevant text, table, or figure for readers to understand the connection. Broader background references may be collected at the end of a lesson and identified as further reading.

We prioritize explicit sourcing for:

• Quantitative values and calculations based on published data.
• Specific research findings and interpretations.
• Debated, developing, or context-dependent explanations.
• Adapted diagrams, tables, datasets, and other third-party materials.
• Assumptions underlying a scientific model or activity.

We avoid padding reference lists with works that were not consulted or that do not contribute to the explanation.

Checking References Before Publication

Contributors should consult the relevant source directly and verify that the cited passage or evidence supports the claim. Access limited to an abstract or summary must not be presented as examination of the full study.

Citation details, links, and identifiers should be checked. Where relevant, this includes looking for corrected versions, expressions of concern, or retraction notices.

A retracted article must not serve as reliable evidence for a scientific claim. If it is discussed for historical or explanatory reasons, its status should be stated clearly. Sources carrying an expression of concern require careful assessment and suitable context.

Preprints should be labeled as preprints, with their review status made clear. Where a later published version exists, contributors should check whether it changes the findings or interpretation.

Reference Information and Format

1Lecture may use numbered references or descriptive links, provided the approach is consistent within a page and readers can identify the cited work.

Reference details should include the information needed to locate the version consulted:

A link should preferably lead to the original publisher, an authorized repository, or the responsible organization. If a secondary source is the material actually consulted, attribution should reflect that fact.

Figures, Tables, Data, and Calculations

Scientific sourcing and media attribution serve related but different purposes. A diagram may need references for its scientific content as well as a credit identifying its creator.

Reused or adapted material must have suitable permission or licensing, and its credit should explain the source and any relevant changes. Citation alone does not establish permission to reproduce a work.

Numerical tables and worked examples should identify their data sources, units, conditions, and transformations. Illustrative or simulated values should be labeled accordingly. Derived results should be distinguishable from values reported directly by a source.

Quiz answer keys and interactive models should have traceable scientific support, even where detailed development notes are retained internally.

AI, Independence, and Citation Integrity

AI-generated answers and fabricated references are not acceptable scientific support. Suggested citations from automated tools must be located and checked by a person before use.

Reference selection must reflect relevance and evidential value. Payment, sponsorship, affiliate relationships, or requests to increase citation counts must not determine which scientific sources support a lesson.

Mentioning or linking to a source does not imply that its authors or organization endorse 1Lecture.

Maintaining Sources and Reporting Problems

Broken links should be repaired when a reliable replacement can be identified. A changed destination must still correspond to the work cited.

New corrections, retractions, or evidence may require reassessing the associated explanation, rather than simply replacing a link. Material changes should follow our corrections process.

Readers can report a missing, inaccurate, or unsuitable citation by identifying the lesson, the statement concerned, and the relevant source or correction.

Background References

• ICMJE — Preparing a Manuscript for Submission to a Medical Journal
• Crossref — Retraction Watch Documentation