	Authors	Year	Title
	Kullmann & Nikolaeva	1995	A Review of Upper Namurian ammonoid biostratigraphy. Newsletters on Stratigraphy, 32: 117-136, 10 figs., Berlin, Stuttgart.
	Wray & Melmore	1934	Notes on some recent deep borings at Huddersfield. Proceedings of the Yorkshire Geological Society 22: 30-51, 1 text-fig., pl.3, Leeds.