00542nam a22001817a 450000500170000001000150001702000260003203500130005803700130007108200080008410000170009224500650010926000350017427000680020930000270027750000500030470000060035420130618121447.0  aENG-107363  a9788120346390c525.00  aEN-90896  bDBAD/PUB  a020  aGurdev Singh  aInformation sources, services and systems /cby Gurdev Singh  aNew DelhibPHI Learning c2013  aRimjhim House, 111, Patparganj Industrial EstatebDelhie110092  axviii,517p.c24cm(pbk)  aIncludes bibliographical references and index  a