Gw mau tau . dari Astrolab. Jelasin dalam bahasa melayu

John David North (2005), God's Clockmaker: Richard of Wallingford and the Invention of Time, Continuum International Publishing Group, ISBN 978-1-85285-451-5

Critical edition of  Pélerin de Prusse on the Astrolabe (translation of Practique de Astralabe). Editors Edgar Laird, Robert Fischer. Binghamton, New York, 1995, in Medieval & Renaissance Texts & Studies. ISBN 0-86698-132-2

King, Henry Geared to the Stars: the Evolution of Planetariums, Orreries, and Astronomical Clocks University of Toronto Press, 1978