Bibby, C. J. (1992). Bird Census Techniques Collin J. Bibby, Neil D. Burges. Academic.
Lua i Stíl Chicago (17ú heag.)Bibby, Collin J. Bird Census Techniques Collin J. Bibby, Neil D. Burges. Academic, 1992.
Lua MLA (8ú heag.)Bibby, Collin J. Bird Census Techniques Collin J. Bibby, Neil D. Burges. Academic, 1992.
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