BUREAU OF INDIAN STA INDIAN STANDARD SUBSURFACE EXPLORATION BY PITS, TRENCHES, DRIFTS AND SHAFTS-CODE OF PRACTICE. IS 445 - 2nd rev. ed. 2009 - NEW DELHI BUREAU OF INDIAN STANDARDS. - 9 Subjects--Topical Terms: PITS, TRENCHES, DRIFTS AND SHAFTS-CODE OF PRACTICE Dewey Class. No.: 624 / BUR