objectif

[1982] The First Aplanatic Object Glass ; J. A. Bennett ; Journal for the History of Astronomy 13 (1982) p. 206 [lien]
[1988] The Object-Glass of the Greenwich Great Equatorial Telescope ; C. M. Lowne ; Journal for the History of Astronomy 19 (1988) p. 169 [lien]
[2007] Frank Ross, his Ross Lens Design, and the Lick Observatory 20-inch Astrograph ; Donald E. Osterbrock ; Journal for the History of Astronomy 38 (2007) p. 31 [lien]