Webb, John W. Programmable logic controllers : principles and applications / John W. Webb, Ronald A. Reis. - 4th ed. - Upper Saddle River, N.J. : Prentice Hall, c1999. - xv, 443 p. : ill. ; 24 cm. Includes bibliographical references (p. 435-437) and index. ISBN: 0136794084 Subjects--Topical Terms: Programmable controllers.