HOWARD GRUBB, PARSONS & CO., 1934

Object glasses, mirrors, etc. for astronomical instruments : Price list : Pamphlet n. 105 / Sir Howard Grubb, Parsons & Co., Optical Works, Walker-Gate, Newcastle upon Tyne, England. – [S.l. : S.n.], [1934?] (London : Industrial Publicity Service). – 8 p. : ill. ; 29 cm.
Testo in inglese. – Sulla 8. p. : 4. 34.