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
cac dai » cac dan, cac bai, can dai
va danh » va dinh, va hanh, dia danh
tu sach » thu sach, su sach, te sach
nang o » nang co, nang ho, nang ro
va dan » ca dan, va dao, va dau
o hoi » co hoi, o hoc, o hai
di su » doi su, ki su, da 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 o hoi. ((hieu vien) or (hieu hien)) cac dai ((va danh) OR (va dan)) di su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang o hoi. ((hieu vien) OR (hieu hien)) cac dai ((va danh) OR (va dan)) di su triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang o hoi. ((hieu vien) or (hieu hien)) cac dai ((va danh) OR (va dan)) di su triet*".