Wikipedia:Citing citations

In academia there is a tendency towards reciting the same paper over and over again, sometimes a paper is cited thousands of times over many decades simply because that is the common way to do things. Sometimes these foundational papers are found to be less than reliable, whereupon literature which builds upon these papers stands on shaky grounds. However, this literature continues receiving citations — resulting in a situation where statements in journal articles are based not on scientific evidence, but based on conjecture.

Examples:
 * Stanford prison experiment
 * Placebo trials

Perpetuation
Sometimes even debunked theories, positions or statements are perpetuated with reference to older and inadequate sources. Wikipedia emphasises the weight of secondary sources over primary sources, but narrative reviews may engage in the same cherry-picking of poor original resources as is prohibited in certain fields on Wikipedia (see Identifying reliable sources (medicine))

This may not be intentionally illicit and is often due to a lack of up-to-date sources available to the authors of the narrative review (i.e. the best sources are not available in their language), or following a poorly performed literature search. This is avoided by systematically searching the literature, and sources that presents a protocol for search are valued higher than one that does not.