1. Ager D. V. (1973) The Nature of the Stratigraphic Record (Macmillan, London), p 114.
2. Planolites and Skolithos from the Upper Precambrian–Lower Cambrian, White-Inyo Mountains, California;Alpert;J. Paleont,1975
3. The type Wenlock Series;Basseit;Rep. Inst. geol. Sci. London,1975
4. Probable orthocone skip and roll marks from the Aberystwyth Grits;Bates;Geol. Mag,1974
5. Discussion and comments on Nicholson's 1872 manuscript ‘Contributions to the study of Errant Annelides of the Older Palaeozoic rocks’;Benton;Publs. Dep. Geol. Miner. Univ. Aberdeen,1978