Perhaps you should try some spelling variations:
hanh kien » danh kien, anh kien, thanh vien
qua tham » qua cham, qua than, qua thanh
kien su » nien su, tien su, vien sau
luc van » luoc van, luu van, duc van
xuc van » duc van, vuc van, xuc ban
te sach » toc sach
sach tu » sach thu, cach tu, sach ty
tang ma » mang may, tang van
nang ma » sang ma, nang cao, mang may
su viet » so viet

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 tu ((nang ma) or (tang ma)) hoi. hieu qua tham ((xuc van) OR (luc van)) hanh kien su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach tu ((nang ma) OR (tang ma)) hoi. hieu qua tham ((xuc van) OR (luc van)) hanh kien su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach tu ((nang ma) or (tang ma)) hoi. hieu qua tham ((xuc van) OR (luc van)) hanh kien su viet".
• Adding a wildcard symbol may retrieve word variants: te sach tu ((nang ma) or (tang ma)) hoi. hieu qua tham ((xuc van) OR (luc van)) hanh kien su viet*.