@book{14257,
	author = {International Astronomical Union and International Astronomical Union Colloquium and Johnston, K. J., ed.},
	title = {Towards models and constants for sub - microarcsecond astrometry},
	publisher = {U. S. Naval Observatory},
	year = {2000},
	series = {IAU Colloquium; no.180},
	address = {Washington, D. C.}
}