Guides to Stratigraphic Procedure and Codes

Rawson etal. (2002). Stratigraphical Procedure. Geological Society, London, Professional Handbook.
Murphy and Salvador (eds.).(1994) International Stratigraphic Guide - An abridged version. ICS.
North American Commission on Stratigraphic Nomenclature (2005). North American stratigraphic code (from The American Association of Petroleum Geologists Bulletin, 89, (11), 1547-1591- pdf version).
Proposals for classifying units of intrusive rock. This report from the BGS sets out a framework and terminology for classifying and naming lithodemic units composed entirely of, or predominantly of, intrusive rock. It has been written with the geology of the UK in mind, but the principles and definitions recommended here should be applicable globally.
Usage of Stratigraphic Terminology in Papers, Illustrations, and Talks by Donald E. Owen (from Journal of Sedimentary Petrology, Vol.57, No.2, 1987)