Pyle, R. M. (1974). Watching Washington butterflies: An interpretive guide to the State's 134 species, including most of the butterflies of Oregon, Idaho, and British Columbia. Seattle Audubon Society.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रPyle, Robert Michael. Watching Washington Butterflies: An Interpretive Guide to the State's 134 Species, Including Most of the Butterflies of Oregon, Idaho, and British Columbia. [Seattle]: Seattle Audubon Society, 1974.
एमएलए (8वां संस्करण) प्रशस्ति पत्रPyle, Robert Michael. Watching Washington Butterflies: An Interpretive Guide to the State's 134 Species, Including Most of the Butterflies of Oregon, Idaho, and British Columbia. Seattle Audubon Society, 1974.
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