Perhaps you should try some spelling variations:
thu thanh » thu thang, tu thanh, thuan thanh
thanh cau » thanh chau, thanh mau, nhanh cau
sach thu » sach thue, sach thieu, sach tham
nam thuc » nam thuoc, am thuc, nam thu
van hanh » van thanh, ban hanh, van ban
so triet » su triet, so thiet, bo triet
su sach » so sach, vu sach
qua nam » quan nam, cua nam, quang nam
van anh » van thanh, tuan anh, van minh
tai so » tai sao, dai so, tai co

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach thu thanh cau hoi. hieu qua nam thuc ((van hanh) or (van anh)) tai so triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach thu thanh cau hoi. hieu qua nam thuc ((van hanh) OR (van anh)) tai so triet.
• Adding a wildcard symbol may retrieve word variants: su sach thu thanh cau hoi. hieu qua nam thuc ((van hanh) or (van anh)) tai so triet*.