If you want the definitive reading, read the four parts of the ISO/ITU ODP standard. Part one is a long introduction. You will find links to these from the ODP host site.
Other interesting reading:
ANSI: Business rules for the Enterprise Viewpoint of RM-ODP. ANSI X3H7-96-07R2, 7 December 1996.
V.Gay and P Leydekkers: Multimedia in the ODP-RM Standard. IEEE Multimedia Vol. 4 no. 1, Jan-March 1997.
H.Kilov and J.Ross: Information modeling: an object-oriented approach. Prentice-Hall, 1994. Chapter 7. Standards.
H. Kilov and L. Redmann: Specifying Joint Behavior of Objects: Formalization and Standardization, Proc. SESS93 (Software Engineering Standards Symposium), Brighton, UK, IEEE Computer Society, 1993, 220-226.
H.Kilov: Precise specification of behavior in object-oriented standardization activities. Computer standards and interfaces, Vol. 15 (1993), No. 2-3, pp. 275-285.
H.Kilov and D.R.Johnson. Can a flat notation be used to specify an OO system: using Z to describe some RM-ODP constructs. In: Proceedings of FMOODS96: IFIP WG 6.1 Conference on Formal Methods in Object-oriented Distributed Systems, Paris, March 1996, pp. 407-418.
Kerry Raymond and Liz Armstrong (editors): Open Distributed Processing: Experiences with distributed environments. Chapman and Hall 1994.