Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh vai » hanh vi, hanh tai, hanh van
sach thi » sach thu, sach tai, sach thieu
cua viet » ca viet, hoa viet, cua vat
thi hanh » thi thanh
hieu va » hieu qua
hanh va » hang va, hanh vi
cac toc » cac toi, cac nuoc, cac thoi
xa hanh » xa thanh, xa khanh, va hanh
vai cua » dai cua, hai cua, lai cua
va hoi » xa hoi, va hoc, va hoa

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 thi hanh va hoi. ((hieu va) or (lieu va)) ((hoc nuoc) or (cac toc)) xa hanh vai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach thi hanh va hoi. ((hieu va) OR (lieu va)) ((hoc nuoc) OR (cac toc)) xa hanh vai cua viet.
• Adding a wildcard symbol may retrieve word variants: toc sach thi hanh va hoi. ((hieu va) or (lieu va)) ((hoc nuoc) or (cac toc)) xa hanh vai cua viet*.