000 00631nab a2200181 4500
005 20260520004038.0
008 260224s2009 xxu
245 0 0 _aNew drillbit offerings keep pushing the envelope
260 _a
_b
_coct. 2009
270 _a26/08/2010 ; 28/07/2010
300 _a4 p. ; 45-48
520 _aTranscripción del resumen del autor. Improvements in hardness and durability have yet to approach a limit. Even roller-cone bits are being improved with new metallurgy.
581 _a10
773 0 _tWorld Oil
_g230
942 _cARTICULO
100 1 _aFischer, Perry
_937095
999 _c175412
_d175412