Subclass	Subgroup	Patent
E21B	7/04	12392198
	10/14	12392199
	10/26	12392200
	10/32	12392201
	10/36	12392202
	17/028	12392203
	21/062	RE050536
	21/08	12392204
		12392205
		12392206
	23/01	12392207
		12392208
	27/04	12392209
	29/005	12392210
	29/02	12392211
	33/1243	12392212
	33/128	12392213
	33/129	12392214
	33/1293	12392215
	33/13	12392216
	33/14	12392217
		12392218
		12392219
	34/14	12392220
	34/16	12392221
	37/06	12392222
	41/0035	12392223
	41/0064	12392224
	41/0085	12392225
	43/086	12392226
	43/106	12392227
	43/117	12392228
	43/123	12392229
	43/26	12392230
	43/2607	12392231
		12392232
	44/04	12392233
	47/0025	12392234
	47/022	12392235
	47/08	12392236
	47/092	12392237
	47/10	12392238
	47/11	12392239
	47/117	12392240
	49/08	12392241
E21C	51/00	12392242
E21D	11/006	12392243