Cite this article:

. . New Technology of Library and Information Service, 1999, 15(6): 47-48.

URL:

https://manu44.magtech.com.cn/Jwk_infotech_wk3/EN/10.11925/infotech.1003-3513.1999.06.14     OR     https://manu44.magtech.com.cn/Jwk_infotech_wk3/EN/Y1999/V15/I6/47