Não informado. Publications of the Allegheny Observatory of the University of Pittsburgh. University of Pittsburgh.
Chicago-Zitierstil (17. Ausg.)Não informado. Publications of the Allegheny Observatory of the University of Pittsburgh. Lancaster, Pa: University of Pittsburgh.
MLA-Zitierstil (8. Ausg.)Não informado. Publications of the Allegheny Observatory of the University of Pittsburgh. University of Pittsburgh.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.