Perhaps you should try some spelling variations:
dat khanh » van khanh, duy khanh
toc sach » hoc sach, doc sach, thuoc sach
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
sach thi » sach thu, sach tai, sach thieu
hanh cau » nhanh cau, hang cau, hanh cac
thi hanh » thi thanh
hieu va » lieu va, hieu qua
cac toc » cac toi, cac thoi
lai va » loai va, mai va, hai va
dai va » mai 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 thi hanh cau hoi. hieu va ((cac nuoc) or (cac toc)) dat khanh ((lai va) or (dai va)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach thi hanh cau hoi. hieu va ((cac nuoc) OR (cac toc)) dat khanh ((lai va) OR (dai va)) triet.
• Adding a wildcard symbol may retrieve word variants: toc sach thi hanh cau hoi. hieu va ((cac nuoc) or (cac toc)) dat khanh ((lai va) or (dai va)) triet*.