Perhaps you should try some spelling variations:
thien quan » trien quang, lien quan, thien van
hieu quan » hieu qua, lieu quan, lien quan
van hanh » van thanh, ban hanh, van anh
phan dam » phan dau, phan cam, phan dai
dam van » dao van, nam van, pham van
te sach » toc sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
mang xa » lang xa, mang may, dang xay
su tien » su kien, su hien, tu tieng
vi su » va su, ve su, ki su

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky ((mang xa) or (nang ma)) hoi. ((hieu quan) OR (thien quan)) phan dam van hanh vi su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky ((mang xa) OR (nang ma)) hoi. ((hieu quan) OR (thien quan)) phan dam van hanh vi su tien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky ((mang xa) or (nang ma)) hoi. ((hieu quan) OR (thien quan)) phan dam van hanh vi su tien".
• Adding a wildcard symbol may retrieve word variants: te sach ky ((mang xa) or (nang ma)) hoi. ((hieu quan) OR (thien quan)) phan dam van hanh vi su tien*.