1. Stratigraphic classification in Precambrian rocks;Allan;Geol. Mag.,1968
2. Code of stratigraphic nomenclature;American Commission on Stratigraphic Nomenclature;Bull. Am. Assoc. Petrol. Geologists,1961
3. Definition of Geologic Systems, by the International Subcommission on Stratigraphic Terminology;American Commission on Stratigraphic Nomenclature;Bull. Am. Assoc. Petrol. Geologists,1965
4. Proposed code for stratigraphical nomenclature;Arkell;Bull. Geol. Soc. Am.,1946