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]