Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach thi » sach thu, sach tai, sach thieu
hanh tai » thanh tai, hang tai, han tai
hanh dai » hanh dao, vanh dai, thanh dat
cua viet » ca viet, hoa viet, cua vat
hanh cac » hang cac, hanh cat, hanh cham
thi hanh » thi thanh
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
cac hoi » cac thoi, cac khoi, cau hoi
nuoc » quoc, duoc, ngoc

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