00297nam a2200109 a 450000500170000002000150001708200160003210000150004824500610006326000420012449000210016620251203110908.0  a8170004128  a025.52bALI  aAli, Amjad  aReference service and the digital sources of information  aNew DelhibEss Ess Publicationsc2004  a392p.d20cm.dHB