Wikipedia:Ye shall know them by their sources

Non-neutral editing will often involve adding poor-quality sources to mainspace articles, because high-quality sources do not support the non-neutral POV, requiring the "POV pusher" to use substandard sourcing in an attempt to meet Wikipedia's verification policy.

Examples of poor sources indicating non-neutral editing include:

• Old sources when new sources are available: e.g., citing 100-year-old scholarship in topic areas that have abundant 21st-century scholarship; citing 100-year-old newspapers reporting on a historical event instead of recent history books that cover the event
• Non-scholarship when scholarship is available: e.g., citing newspapers or magazines instead of scholarship for science topics; citing non-WP:MEDRS for biomedical information
• Non-independent sources when independent sources exist: e.g., using a tobacco company report as a source about the safety of smoking
• Opinions used to source statements of fact: e.g., using an op-ed piece as a source for a statement of fact in Wikipedia's voice
• Primary sources to rebut secondary sources: e.g., citing a primary source, such as the text of a law, in an attempt to rebut or provide false balance for secondary sources, such as law review articles
• Many poor sources: e.g., citing 10 newspaper articles from 100 years ago, but zero history books
• No sources at all: failure to use any reliable sources to support an edit may signify that reliable sources do not support the edit

The above examples do not always indicate non-neutral editing; editors may sometimes use substandard sources for legitimate reasons. For example, an old source may be cited in an article because it is being directly discussed in the prose of the article. As another example, editors may look at primary sources to determine whether a secondary source made a typographical or other clear error, or to resolve conflicts between secondary sources. Rarely will any single edit or talk page argument provide "smoking gun" proof of non-neutral editing; rather, non-neutral editing will be signified by a pattern of using poor sources.

In addition to the use of poor sources, non-neutral editing may also involve the misuse of high-quality sources, because the proper use of such sources will not support the non-neutral POV.

Examples of misuse of reliable sources indicating non-neutral editing include:

• Cherrypicking sources: e.g., citing only sources that hold a particular viewpoint, while excluding sources of equal or greater quality that contradict that viewpoint
• Misquoting sources: e.g., using partial quotes that omit relevant context
• Overrepresentation of sources: e.g., "Most scholars say X" followed by citations to scholars saying X, but no source that says most scholars say X
• Underrepresentation of sources: e.g., "Scholar [name] says X" when, in fact, the overwhelming majority of sources say X
• Using expert sources outside their field of expertise: e.g., citing a poetry professor to support a statement about biology or international relations

• WP:Identifying and using primary sources
• WP:Identifying and using tertiary sources
• WP:Independent sources
• WP:Frequently misinterpreted sourcing policy
• WP:POV and OR from editors, sources, and fields
• WP:Tiers of reliability