Muir and Sarjeant, 1978
From dinoflaj3
Muir, M.D. and Sarjeant, W.A.S., 1978: The palynology of the Langdale Beds (Middle Jurassic) of Yorkshire and its stratigraphical implications. Review of Palaeobotany and Palynology, v.25, p.193-239, pl.1-7.