00305nam a2200121 a 450000500170000002000150001708200200003210000220005224500350007425000120010926000400012130000220016120251202164245.0  a0201031833  a001.64,bD, Dav  aDavis, William S.  aInformation processing systems  a2nd ed.  aLoNew DelhionbAddison-Wesleyc1981  axix,504p.c21 cm.