Perhaps you should try some spelling variations:
tuan doanh » toan doanh, nhuan doanh, tuan anh
doanh khoa » toan khoa
sach tren » sach tien, sach tranh
tren tuan » tran tuan, trung tuan, tren trang
thai sinh » thai binh, phai sinh, tai sinh
sinh khoa » sinh hoc, sinh hoat, anh khoa
khoa hai » khoa hoi, khoa tai, khoa bai
sanh khi » sinh khoi, manh khai, san chi
khi thai » khai thac, thi thao, khi hau
khoa han » khoa than, hoa han, khoa can
tu sach » thu sach, su sach, te sach
so sanh » do sanh
tong » cong, dong, song

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu sach tren tuan doanh khoa hai phong ) or ( so sanh khi thai sinh khoa han tong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach tren tuan doanh khoa hai phong ) OR ( so sanh khi thai sinh khoa han tong )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach tren tuan doanh khoa hai phong ) or ( so sanh khi thai sinh khoa han tong ))*.