↑ Needham, Joseph. (1986). Science and Civilization in China: Volume 4, Physics and Physical Technology; Part 2, Mechanical Engineering. Taipei: Caves Books Ltd. Muka surat 229.
↑ Francis C. Moon, The Machines of Leonardo da Vinci and Franz Reuleaux: Kinematics of Machines from the Renaissance to the 20th Century, ms 314, Springer, 2007 ISBN 1-4020-5598-6.
