00613nam a2200193Ia 4500 CTU_124861 210402s9999 xx 000 0 und d 63.00 025.524 S617/Vol.2 Singh, Sewa Manual of reference and information sources Sewa Singh Ashok Vihar, Delhi B. R. Publishing Corporation 2004 Electronic reference sources,Reference services (Libraries),Electronic reference services (Libraries) Minh Trung tâm Học liệu Trường Đại học Cần Thơ