Bolli, H. M. 1957. Planktonic Foraminifera from the Oligocene - Miocene Cipero and Lengua formations of Trinidad, B.W.I. (215): 97-124.
Blow, W. H. 1959. Age, correlation, and biostratigraphy of the Upper Tocuyo (San Lorenzo) and Pozon Formation, Eastern Falcon, Venezuela. 39 (n.178): 59-252.