1. Crosby , E. J.Proc. 1st ICLASS, Tokyo , 435 1978
2. Hayashi , S. , and Takeda , S.Proc. 4th IDS, Kyoto , 384 ( 1984 )
3. Matsumoto , S. , and Takasima , Y.1st ICLASS, Tokyo , 79 , ( 1978 )
4. Toei , R. , Kanso Sochi , pp 227 – 229 ,Nikkankogyo-Sya, Tokyo ( 1966 )