1. Bailey, T. L. — «The Gueydan, a new Middle Tertiary Formation from the south-west coastal plain of Texas». Univ. of Texas Bull. No. 2645, 1926.
2. Blyth, F. G. H. — «Pyroclastic Rocks from the Stapeley Volcanic Group at Knotmoor, near Minsterley, Shropshire». Proc. Geol. Assoc. vol. XLIX, part. 4, 1938, pp. 392–404.
3. Harker, A. — «Petrology for Students». (1st edition). Cambridge, 1895.
4. Hatch, F. H. &A. K. Wells — «Petrology of the Igneous Rocks» (9th edition). Allen & Unwin Ltd., London, 1937.
5. Holmes, A. — «Nomenclature of Petrology» (2nd edition). Thomas Murby & Co., London, 1928.