Note 540 — Chapter XII · THE SPIRAL SHELLS OF THE FORAMINIFERA
Reading edition
Rhumbler, L., Die Doppelschalen von Orbitolites und anderer Foraminiferen, etc., Arch. f. Protistenkunde, I, pp. 193–296, 1902; and other papers. Also Die Foraminiferen der Planktonexpedition, I, 1911, pp. 50–56.