Özcan, E., Sirel, E., Özkan-Altiner, S., & Çolakoğlu, S. (2001). Late Paleocene Orthophragminae (Foraminifera) from the Haymana-Polatli Basin, central Turkey and description of a new taxon, Orbitoclypeus haymanaensis. Micropaleontology. 47(4): 339-357.
Özcan, E., Sirel, E., Özkan-Altiner, S., & Çolakoğlu, S.
2001
Late Paleocene Orthophragminae (Foraminifera) from the Haymana-Polatli Basin, central Turkey and description of a new taxon, Orbitoclypeus haymanaensis