Thomsen and Heilmann-Clausen, 1985
From dinoflaj3
Thomsen, E. and Heilmann-Clausen, C., 1985: The Danian-Selandian boundary at Svejstrup with remarks on the biostratigraphy of the boundary in western Denmark. Bulletin of the Geological Society of Denmark, v.33, p.341-362, pl.1-7.