Guerstein et al., 2001
From dinoflaj3
Guerstein, G.R, Williams, G.L and Fensome, R.A., 2001: Cannosphaeropsis quattrocchiae, a new species of dinoflagellate cyst from the mid Cenozoic of the Colorado Basin, Argentina. Micropaleontology, v.47, p.155-167, pl.1-2.