2 literature references for Esperia collina (Bowerbank, 1882):

Author: Bowerbank, J.S.; Norman, A.M.
Year: 1882
Title: A Monograph of the British Spongiadae. Volume 4 (Supplement).
Source: (Ray Society: London):i-xvii, 1-250, pls I-XVII.
Author: Arndt, W.
Year: 1935
Title: Porifera.
Source: In: Die Tierwelt der Nord- und Ostsee. 3a (27).(Leipzig): 1-140.