00450nam a22001097a 4500008004100000040005500041245016600096260004500262300001100307650001600318650000600334230524b        |||||||| |||| 00| 0 eng d  aNational Science LibrarycNational Science Library  aProceedings of symposium on drilling technology and engineering aids to geological exploration, Calcutta 12th to 15th February 198c/ Geological Survey of India   aNew Delhi: bGovernment of India, c1980  a637p.   aGeological   a