1. IAG SSG5.123. Definition and realization of terrestrial reference systems;Boucher;Report 1987–1991,1991
2. Development of a Conventional Terrestrial Reference Frame;Boucher;CDP Monograph.,1992
3. Realization of the IERS Terrestrial Reference System;Altamimi,1991
4. 1991 IERS Annual Report,1992
5. ITRF91 and its associated velocity field;Boucher,1992