Perhaps you should try some spelling variations:
qua tham » qua cham, qua than, qua thanh
van hanh » van thanh, ban hanh, van anh
tham xuc » tham nuoc, tham thuc, pham duc
hanh ki » hanh vi, hanh ky, hanh kien
xuc van » duc van, luc van, vuc van
sach tu » sach thu, cach tu, sach ty
tu sach » thu sach, su sach, te sach
tang ma » mang may, tang van
nang ma » sang ma, nang cao, mang may
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 ki ((su viet) OR (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 ki ((su viet) OR (so viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach tu ((nang ma) or (tang ma)) hoi. hieu qua tham xuc van hanh ki ((su viet) OR (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 ki ((su viet) OR (so viet))*.