 The Homogeneous Coordinate Ring of a Toric Variety by David A. Cox

Original article, Journal of Algebraic Geometry4 (1995),17–50; author-hosted version: arxiv.org/pdf/alg-geom/9210008 . The inspected arXivv3 PDF includes the1993 revision and states the ray-span assumption in section1, the polynomial class grading and irrelevant ideal in section1, and categorical/geometric quotient theorem in section2.