1. William H. Beyer (ed.), CRC Standard Mathematical Tables, 27th Edition, CRC Press, Boca Raton, FL, 1984. p. 194.
2. Harry Bouchard and Francis H. Moffit, Surveying, 5th edition, International Textbook Company, Scranton, PA, 1965, p. 228.
3. A Mnemonic for Areas of Polygons