Cite this article:

. . New Technology of Library and Information Service, 1992, 8(4): 46-48.

URL:

https://manu44.magtech.com.cn/Jwk_infotech_wk3/EN/10.11925/infotech.1003-3513.1992.04.11     OR     https://manu44.magtech.com.cn/Jwk_infotech_wk3/EN/Y1992/V8/I4/46