3 literature references for Calthropella stelligera (Schmidt, 1868):

Author: Van Soest, R.W.M.
Year: 2001
Title: Porifera, in: Costello, M.J. et al. (Ed.) (2001).
Source: European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification. Collection Patrimoines Naturels, 50:
Author: Schmidt, O.
Year: 1868
Title: Die Spongien der Küste von Algier. Mit Nachträgen zu den Spongien des Adriatischen Meeres (Drittes Supplement).
Source: (Wilhelm Engelmann: Leipzig): i-iv, 1-44, pls I-V.
Author: Voultsiadou, E.; Vafidis, D.
Year: 2004
Title: Rare sponge (Porifera: Demospongiae) species from the Mediterranean Sea.
Source: Journal of the Marine Biological Association of the United Kingdom 84 (3): 593-598.