00496nam a2200169Ia 4500 CTU_47430 210402s9999 xx 000 0 und d 515.9 Th561 Trương Văn Thương Hàm số biến số phức Trương Văn Thương Hà Nội Giáo Dục 2002 functions of complex variables Trung tâm Học liệu Trường Đại học Cần Thơ