1950 108 p., 26 figs, 9 pls, 1 fold. & col. map, paperbound. Title-page missing? Published in: Leidse Geol. Mededelingen.
1954 245 p., 78 figs, 7 pls (depicting mostly foraminiferans and ostracodes), 4 folded maps, paperbound. Published in: Verhandelingen der Koninklijke Nederlandse Akademie van Wetenschappen.