Não informado. (1935). Contributions from the Perkins Observatory. Ohio State University, Ohio Wesleyan University.
Citação do estilo Chicago (17ª ed.)Não informado. Contributions from the Perkins Observatory. Delaware, Ohio: Ohio State University, Ohio Wesleyan University, 1935.
Citação MLA (8ª ed.)Não informado. Contributions from the Perkins Observatory. Ohio State University, Ohio Wesleyan University, 1935.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.