00503nam a22001337a 4500 230524b |||||||| |||| 00| 0 eng d National Science Library National Science Library Proceedings of symposium on drilling technology and engineering aids to geological exploration, Calcutta 12th to 15th February 198 / Geological Survey of India New Delhi: Government of India, 1980 637p. Geological udc PR 58302 58302 0 0 udc 0 0 111185 NSL NSL FF/Rk-2/C-15/R-6 2023-08-08 0 80306 2023-08-08 00:00:00 2023-08-08 PR