Ewins, P., Ewins, P., & Perrins, C. (1986). The ecology of black guillemots Cepphus grylle in Shetland.
Lua i Stíl Chicago (17ú heag.)Ewins, P., Pete Ewins, agus C. Perrins. The Ecology of Black Guillemots Cepphus Grylle in Shetland. 1986.
Lua MLA (9ú heag.)Ewins, P., et al. The Ecology of Black Guillemots Cepphus Grylle in Shetland. 1986.
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