Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
hanh lai » hanh lam, hanh tai, thanh lap
hieu van » hieu va, thien van, lieu va
sach thu » sach thue, sach thieu, sach tham
nang ma » tang ma, sang ma, nang cao
sach ty » sach y, sach tu, xach tay
van cac » van hac, van cau, van bac
ma hoi » mai hoi, xa hoi, ma hoa
xuc va » duc va, luc va, xac va
tuc va » thuc va, truc va, tuc xa

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)) nang ma hoi. hieu van cac ((xuc va) OR (tuc va)) hanh lai su triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) or (sach thu)) nang ma hoi. hieu van cac ((xuc va) OR (tuc va)) hanh lai su triet~".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) or (sach thu)) nang ma hoi. hieu van cac ((xuc va) OR (tuc va)) hanh lai su triet*.