Document Type and Number:
Japanese Patent JPS5629436
Kind Code:
Y2
Application Number:
JP8988078U
Publication Date:
July 13, 1981
Filing Date:
June 29, 1978
Export Citation:
International Classes:
E21B17/03; E21B1/00; E21B15/00; E21B17/00; E21B19/24; (IPC1-7): E21B17/00; E21C9/00