12 1 50 Alan S Donnahoe Additional Author mixed material John Wiley & Sons 1988 Philips G. Enns Additional Author mixed material Richard D.Irwin 1985 methods Philip G. Enns Additional Author mixed material Richard D. Irwin 1985 Terry Sincich Additional Author mixed material Macmillan Pub. 1990 Philip G. Enns Additional Author mixed material Richard D. Irwin 1985 Owen P. Hall Additional Author Harvey E. Adelman Additional Author mixed material Irwin 1991 David F Groebner Additional Author Patrick W Shannon Additional Author mixed material Macmillan Pub. (sa) the modern approach J.E. Freud Additional Author F.J. Williams Additional Author mixed material Prentice Hall 1982 the modern approacs J.E Freud Additional Author F.J Williams Additional Author mixed material Prentice Hall 1982 Charles L Olson Additional Author Marid J Pieconi Additional Author mixed material McGraw Hill 1983 Isabel S Patchett Additional Author mixed material Van Nostrand 1982 James T Mc Clave Additional Author P George Benson Additional Author mixed material Collier Macmillan 1985