Document Type and Number:
Japanese Patent JPS52131801
Kind Code:
U
Application Number:
JP4054076U
Publication Date:
October 06, 1977
Filing Date:
April 01, 1976
Export Citation:
International Classes:
E21B1/00; E02F3/02; E02F5/20; (IPC1-7): E02F3/02; E02F5/20
Domestic Patent References:
JPS4921805B1 | 1974-06-04 |