Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
hieu van » hieu va, thien van, lieu va
te sach » toc sach
sach ky » sac ky, sach y, sach ty
nang ma » sang ma, nang cao, mang may
tang ma » mang may, tang van
van hoc » van hoa
duc van » duc va, duc manh, duc phan
cua tu » cua tuc, cua su, cua cu

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: te sach ky ((nang ma) OR (tang ma)) hoi. hieu van hoc ((duc van) OR (duc tan)) thanh dai cua tu~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky ((nang ma) or (tang ma)) hoi. hieu van hoc ((duc van) OR (duc tan)) thanh dai cua tu~".
• Adding a wildcard symbol may retrieve word variants: te sach ky ((nang ma) or (tang ma)) hoi. hieu van hoc ((duc van) OR (duc tan)) thanh dai cua tu*.