Document Type and Number:
Japanese Patent JPH0447272
Kind Code:
Y2
Application Number:
JP3831886U
Publication Date:
November 09, 1992
Filing Date:
March 18, 1986
Export Citation:
International Classes:
E21B10/18; E21B3/00; E21B7/02; (IPC1-7): E21B7/02; E21B3/00
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