P. S.E. Maxwell Modern Methods of Time Recording as used in H. B. M. Hydrographic Service PDF (English)
Sanford L. Cluett Determination of Offshore Position by Sextant Altitude of Mountain Peak PDF (English)
P. M. Van Riel The Snellius Expedition in the Eastern Part of the Netherlands East Indies 1929-1930 PDF (English)
Youssouf Kamal A few scattered explanations on my Monumenta Cartografica Africae & Aegypti PDF (English)