Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
thi hanh » thi thanh
va hanh » van hanh, va thanh, va danh
cac duc » cao duc, cac dac, cac nuoc
tu sach » thu sach, su sach, tu cach
hanh va » hang va, hanh vi
te sach » toc sach
hieu ve » hieu va, hieu van
va hoi » xa hoi, va hoc, va hoa
kem va » kiem va, kiem van

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) or (te sach)) thi hanh va hoi. hieu ve ((cac duc) or (cac du)) va hanh kem va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) thi hanh va hoi. hieu ve ((cac duc) OR (cac du)) va hanh kem va triet.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (te sach)) thi hanh va hoi. hieu ve ((cac duc) or (cac du)) va hanh kem va triet*.