Não informado. Publications of the Allegheny Observatory of the University of Pittsburgh. University of Pittsburgh.
Citação do estilo Chicago (17ª ed.)Não informado. Publications of the Allegheny Observatory of the University of Pittsburgh. Lancaster, Pa: University of Pittsburgh.
Citação MLA (8ª ed.)Não informado. Publications of the Allegheny Observatory of the University of Pittsburgh. University of Pittsburgh.
Предупреждение: эти цитированмия не могут быть всегда правильны на 100%.