Perhaps you should try some spelling variations:
hieu hien » bieu hien, dieu hien, chieu chien
hieu vien » hieu viec, thieu nien, hieu tieng
su triet » su viet, su tien, ve triet
sach ky » sac ky, sach y, sach ty
hanh ki » hanh vi, hanh ky, hanh kien
tu sach » thu sach, su sach, te sach
x hoi » xa hoi, o hoi, x ho
ki su » ky su

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 ky nang x hoi. ((hieu vien) or (hieu hien)) cac ((dai va) OR (mai va)) hanh ki su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. ((hieu vien) OR (hieu hien)) cac ((dai va) OR (mai va)) hanh ki su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. ((hieu vien) or (hieu hien)) cac ((dai va) OR (mai va)) hanh ki su triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. ((hieu vien) or (hieu hien)) cac ((dai va) OR (mai va)) hanh ki su triet*.