↑ Clark, John Spencer (1895), Teachers' Manual: Books I-VIII.. For Prang's complete course in form-study and drawing, Books 7–8, Prang Educational Company, p. 49. ↑ Fontaine, Michael (2010), Funny Words in Plautine Comedy, Oxford University Press, pp. 117, 154, ISBN 9780195341447. ↑ William F. Kern, James R. Bland, Solid Mensuration with proofs, 1938, p. 67 ↑ Nahin, Paul. An Imaginary Tale: The story of √−1.