(1) Estimation & Costing by B.N. DUTTA
https://drive.google.com/file/d/1TsG32d5bspMwx0xIoMsU5_Gn45amxMGk/view
(2) Estimating, Costing, Specification & Valuation in Civil Engineerings by M CHAKRABORTI
https://drive.google.com/file/d/1Fpl5-IZk-6iSdF8FAs-VovmR1LErLPVJ/view
