Online citation analysis - A methodological approach. - Finn Hjortgaard Christensen; Peter Ingwersen (Scientometrics, 1996)

Data Set Isolation for Bibliometric Online Analyses of Research Publications: Fundamental Mehodological Issues. - Peter Ingwersen; Finn Hjortgaard Christensen (J. Am. Soc. Inf. Sci., 1997)

Online determination of the journal impact factor and its international properties. - Finn Hjortgaard Christensen; Peter Ingwersen; Irene Wormell (Scientometrics, 1997)