Biffi and Manum, 1988
From dinoflaj3
Biffi, U. and Manum, S.B., 1988: Late Eocene-Early Miocene dinoflagellate cyst stratigraphy from the Marche Region (central Italy). Bollettino della Società paleontologica italiana, v.27, no.2, p.163-212, pl.1-15.