Not all scientific information can be neatly found in handbooks, encyclopedias or published articles. Please look at the gray literature sections (preprints, standards, patents, etc.) for ideas on how to track down harder-to-find materials.
Originated from "Evolution of Scientific Information." From Allan Kent and Harold Lancour, eds., Encyclopedia of Library and Information Science (New York, 1979), s.v. "Scientific Literature," by K. Subramanyam, 394, this diagram was adapted by Timken Science Library, College of Wooster.