Second order bibliometric operators in the Astrophysics Data System
Michael J. Kurtz, G. Eichhorn, Alberto Accomazzi, Carolyn Stern Grant, S. S. Murray · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2002
Second order relational operators are functions which take lists which have been generated by a database query, and from those lists form sets of other lists, which can then be merged and sorted on the basis of one or more of the attributes of the items in the lists. The NASA Astrophysics Data System is unique among bibliometric information retrieval systems in the degree to which users are permitted to make use of these concepts. Given a knowledge of how the second order operators work, ADS users can create complex logical algebras which facilitate the discovery of very highly specific information.