1. Note 32: Definition of geologic systems;Bulletin of the American Association of Petroleum Geologists,1965
2. Jurassic stages;Ager;Nature,1963
3. The Stratigraphic Code and what it implies;Ager,1984
4. The Nature of the Stratigraphic Record;Ager,1994
5. Global review of the Devonian-Carboniferous boundary: An introduction;Aretz;Palaeobiodiversity and Palaeoenvironments,2021