Perhaps you should try some spelling variations:
hieu vien » hieu viec, thieu nien, hieu tieng
hieu hien » bieu hien, dieu hien, chieu chien
sach thu » sach thue, sach thieu, sach tham
va hanh » van hanh, va thanh, va danh
truc va » thuc va, thuc vat, trung va
da truc » dai truc, ba truc, doan truc
sach ty » sach y, sach tu, xach tay
hang ma » hang va, hang ca, tang ma
ma hoi » mai hoi, xa hoi, ma hoa
vi cua » vai cua, di cua

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

• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach thu)) hang ma hoi. ((hieu vien) OR (hieu hien)) da truc va hanh vi cua vat~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) or (sach thu)) hang ma hoi. ((hieu vien) OR (hieu hien)) da truc va hanh vi cua vat~".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) or (sach thu)) hang ma hoi. ((hieu vien) OR (hieu hien)) da truc va hanh vi cua vat*.