Two medical literatures that are logically but not bibliographically connected

This study demonstrates that certain unintended logical connections within the scientific literature, connections potentially revealing of new knowledge, are unmarked by reference citations or other bibliographic clues. Specifically, 25 biomedical articles central to the argument that dietary fish oil causes certain blood changes are compared with 34 articles on how similar blood changes might ameliorate Raynaud's disease. The two groups of articles are thus connected by a chain of reasoning implicitly suggesting that dietary fish oil might benefit Raynaud patients, an hypothesis not heretofore published explicitly. By retrieving and bringing together these two literatures, that implicit, unstated, and perhaps unnoticed hypothesis becomes apparent. The more general problem is posed of whether systematic search techniques for bringing together logically connected literatures can be developed and described, in the hope of discovering other implicit, unstated hypotheses. The example analyzed shows that the problem, while solved in this case by trial‐and‐error search methods, may be inherently and peculiarly difficult because there are virtually no references in either literature to the other, nor are there any clues from cocitation, bibliographic coupling, or statistical association of descriptors that the two literatures are logically related. © 1987 John Wiley & Sons, Inc.