Perhaps you should try some spelling variations:
hanh kien » danh kien, anh kien, thanh vien
qua tham » qua cham, qua than, qua thanh
tham xuc » tham nuoc, tham thuc, pham duc
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
sach tu » sach thu, cach tu, sach ty
nang ma » sang ma, nang cao, mang may
tang ma » mang may, tang van
xuc van » duc van, luc van, vuc van
kien so » khien so, bien so, kien co
so viet » hoc viet

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach tu ((nang ma) or (tang ma)) hoi. hieu qua tham xuc van hanh kien so viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach tu ((nang ma) OR (tang ma)) hoi. hieu qua tham xuc van hanh kien so viet.
• Adding a wildcard symbol may retrieve word variants: tu sach tu ((nang ma) or (tang ma)) hoi. hieu qua tham xuc van hanh kien so viet*.