Gould, Rupert T. John harrison and his timekeepers/ Rupert T. Gould - 4th ed. - Greewich: National Maritime Museum, 1978 - 22 p.: ill.; 21 cm. ISBN: £ 0.35 Subjects--Personal Names: Harrison, John Subjects--Topical Terms: Clocks and watches--HistoryHorology--History Dewey Class. No.: 681.113