Spectroscope and Spectrograph constructed by J.A. Brashear, Allegheny, Pa., USA, for Prof. C.A. Young, Halstead Observatory, Princeton, New Jersey (titre original)

W.S. Bell & Co, “Spectroscope and Spectrograph constructed by J.A. Brashear, Allegheny, Pa., USA, for Prof. C.A. Young, Halstead Observatory, Princeton, New Jersey (titre original),” Bibliothèque numérique - Observatoire de Paris, consulté le 3 mai 2024, https://bibnum.obspm.fr/ark:/11287/1JG7W.