Rexfort, A.; Mutterlose, J. (2006). "Stable isotope records from Sepia officinalis — a key to understanding the ecology of belemnites?". Earth and Planetary Science Letters. 247 (3–4): 212. Bibcode:2006E&PSL.247..212R. doi:10.1016/j.epsl.2006.04.025.
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Rexfort, A.; Mutterlose, J. (2006). "Stable isotope records from Sepia officinalis — a key to understanding the ecology of belemnites?". Earth and Planetary Science Letters. 247 (3–4): 212. Bibcode:2006E&PSL.247..212R. doi:10.1016/j.epsl.2006.04.025.