Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
cau phuc » cau truc, chau phu, huu phuc
cau tren » cu tren, dau tren, ca tren
lai hoi » dai hoi, lai hoa, lai roi
mai hoi » mai khoi, dai hoi, mai doi
hieu ve » hieu va, hieu van
sach ky » sac ky, sach y, sach ty
cau luc » cau truc
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
vi cau » va cau, ve cau, di cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ky nang ((mai hoi) OR (lai hoi)). hieu ve ((cau luc) or (cau phuc)) va dan vi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ky nang ((mai hoi) OR (lai hoi)). hieu ve ((cau luc) OR (cau phuc)) va dan vi cau tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ky nang ((mai hoi) OR (lai hoi)). hieu ve ((cau luc) or (cau phuc)) va dan vi cau tren*".