Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
thi hanh » thi thanh
hanh vai » hanh vi, hanh va, hanh tai
va triet » va thiet, va trien, ve triet
doc sach » hoc sach, nuoc sach, dac sac
hanh ca » hanh cac, hanh cat, hanh cua
hieu va » lieu va, hieu qua
ca hoi » cau hoi, cua hoi, xa hoi
va cao » va cac, va co, va dao
tuc va » thuc va, truc va, duc va
vai va » mai va, dai va, hai va

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sach) or (doc sach)) thi hanh ca hoi. hieu va cao ((tuc va) or (tuc xa)) hanh vai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) thi hanh ca hoi. hieu va cao ((tuc va) OR (tuc xa)) hanh vai va triet.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) thi hanh ca hoi. hieu va cao ((tuc va) or (tuc xa)) hanh vai va triet*.