02a0011779;¥105.76;20011205d1900 ekmy0engy01;eng;a z 100yy;r;Paper of drilling symposium 1987;ed. by R.W. Welch;New York;The American Society of Mechanical Engineers;1987;63 p.;a660.8;Welch;R.W.;Drilling Symposium 1987;1987;101;445114;660.8;W44/87;r¥105.76;a05;b1