2 literature references for Esperia armata (Bowerbank, 1866):

Author: Bowerbank, J.S.
Year: 1866
Title: A Monograph of the British Spongiadae. Volume 2. (
Source: Ray Society: London): i-xx, 1-388.
Author: Fristedt, K.
Year: 1885
Title: Bidrag till Kännedomen om de vid Sveriges vestra Kust lefvande Spongiae.
Source: Kungliga Svenska vetenskapsakademiens handlingar21: 1-56, pls I-IV.