Perhaps you should try some spelling variations:
qua tham » qua cham, qua than, qua thanh
tu sach » thu sach, su sach, te sach
sach tu » sach thu, cach tu, sach ty
tang ma » mang may, tang van
xuc van » luc van, vuc van, xuc ban
duc van » duc va, duc tan, duc manh
hanh ki » hanh vi, hanh ky, hanh kien
su viet » so viet
ki su » ky su

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 cao) or (tang ma)) hoi. hieu qua tham ((xuc van) or (duc van)) hanh ki su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach tu ((nang cao) OR (tang ma)) hoi. hieu qua tham ((xuc van) OR (duc van)) hanh ki su viet.
• Adding a wildcard symbol may retrieve word variants: tu sach tu ((nang cao) or (tang ma)) hoi. hieu qua tham ((xuc van) or (duc van)) hanh ki su viet*.