Also known as gray literature
materials produced by organizations outside of traditional channels
via PubMed
灰色文獻（Grey Literature）介於正式發行的，與不公開出版並深具隱密性的之間，雖已出版但難依一般方式購得。
Abstract from DBpedia / Wikipedia · CC BY-SA
via Wikidata · CC0
via Wikidata sitelinks · CC0
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).