Some of the least permissible articles are those whose lone source cited is published by the article subject's organization. This constitutes a conflict of interest. Any company, organization, group, or individual interest has the ability to publish promotional material about itself.
In some cases, this self-published material may resemble properly published material in many ways.
A paper by a political think tank or lobby group may cite a large number of sources and contain references formatted according to the norms of a journal article. The organization may call itself an "Institute" or "Research Unit". The paper looks like a paper from a peer-reviewed journal – but the two papers are completely different in terms of their reliability. The think tank or lobby group paper was published by an advocacy group, whereas a scholarly paper must be submitted to review by the top experts in the field, corrected by the author, and it is then published by an independent journal with a reputation for fact-checking and accuracy.
Self-published sources do not demonstrate that people independent of the subject consider it notable enough to be worthy of attention. Therefore, self-published sources cannot be used to establish notability. At the same time, non-promotional information of non-controversial validity may be taken from a self-published source after notability has been established.
An article that relies entirely on information from the subject itself may be deleted, possibly under speedy deletion criteria G11, if a reasonable search shows there are no independent sources.