Jabarkan Catatan dari Jam astronomis

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Tor Sørnes. (2008). The Clockmaker Rasmus Sørnes. Borgarsyssel Museum, Sarpsborg, 2003 Norwegian edition, and 2008 English edition (available from the museum).

King, Henry. (1978). Geared to the Stars: the evolution of planetariums, orreries, and astronomical clocks, University of Toronto Press.