Perhaps you should try some spelling variations:
dang khoi » dung khoa, hang khoa
hieu van » thien van, lieu va, hieu ve
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
nuoc van » nuoc va, nuoc san, luoc van
van dang » van dong, van dung, van nang
khoi cua » hoi cua, khi cua, kho cua
sach ky » sac ky, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
cua tu » cua tuc, cua su, cua cu

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat ((sach ky) or (sach y)) nang xa hoi. ((hieu van) OR (hieu va)) cac nuoc van dang khoi cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat ((sach ky) OR (sach y)) nang xa hoi. ((hieu van) OR (hieu va)) cac nuoc van dang khoi cua tu*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat ((sach ky) or (sach y)) nang xa hoi. ((hieu van) OR (hieu va)) cac nuoc van dang khoi cua tu*".