Bibliographic details:
C. Boucher, Z. Altamimi, L. Duhem: ITRF 91 and its associated velocity field. (IERS Technical Note ; 12) Paris: Central Bureau of IERS - Observatoire de Paris, 1992. iii, 143 p.
IERS Technical Note 12: ITRF 91 and its associated velocity field (not accessible) [PDF, 5 MB]

