1. The non-equivalence of the Bradford, Leimkuhler and Lotka ‘laws’;Burrell,1990
2. The duality of informetric systems with applications to the empirical laws;Egghe,1989
3. The duality of informetric systems with applications to the empirical laws;Egghe;Journal of Information Science,1990
4. A note on different Bradford multipliers;Egghe;Journal of the American Society for Information Science,1990
5. New Bradfordian laws, equivalent with old Lotka laws, evolving from a source-item duality argument;Egghe,1990