Não informado. (1935). Contributions from the Perkins Observatory. Ohio State University, Ohio Wesleyan University.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Contributions from the Perkins Observatory. Delaware, Ohio: Ohio State University, Ohio Wesleyan University, 1935.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Contributions from the Perkins Observatory. Ohio State University, Ohio Wesleyan University, 1935.
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