Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
cau phuc » chau phu, huu phuc, van phuc
hieu ke » hieu kem, chieu ke, hieu ky
cao hoi » cau hoi, co hoi, cao hoc
sach ky » sac ky, sach y, sach ty
va dan » ca dan, va dao, va dau
va cai » va cac, va bai, va dai
va ca » va cac, va cao, va 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 cao hoi. hieu ke ((cau phuc) OR (cau truc)) va dan ((va ca) or (va cai)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ky nang cao hoi. hieu ke ((cau phuc) OR (cau truc)) va dan ((va ca) OR (va cai)) tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ky nang cao hoi. hieu ke ((cau phuc) OR (cau truc)) va dan ((va ca) or (va cai)) tren".
• Adding a wildcard symbol may retrieve word variants: hoc sach ky nang cao hoi. hieu ke ((cau phuc) OR (cau truc)) va dan ((va ca) or (va cai)) tren*.