00385nam a22001217a 4500020001800000040000900018082001600027100003000043110003500073245006700108260003800175650005000213  a9789332555402  cNUST  a005.12bGAM  aErich Gamma, Richard Helm  aRalph Johnson , John Vlissides  aDesign PatternsbElements of Reusable Object Oriented Software  aIndia:bPearson Education,c2018.  aElements of Reusable Object Oriented Software