Citation and co-citation indicators of a phased impact of the BCS theory in the physics of superconductivity

An intellectual account of of the physics of superconductivity was compared with citation and co-citation data during two historical periods that coincided with the introduction of its central explanatory theory (BCS). Factor analysis is used to investigate the co-citation data. The results give preliminary support to a hypothesis that distinguishes impact phases in the effect of the theory on the cognitive organization of the specialty. It is also observed that citation and co-citation data are separate types of information which, under some historical conditions, give differing results.