Perhaps you should try some spelling variations:
tu tieng » luc tieng, tu tuong, tu trong
su triet » su viet, su tien, ve triet
sach vu » sach va, sach tu, sach uu
hanh ki » hanh vi, hanh ky, hanh kien
luu van » cuu van, luan van, luu hanh
tu sach » thu sach, su sach, te sach
luc van » luoc van, duc van, luc va
qua cam » qua cham, qua cac, qua ca
nang ma » tang ma, sang ma, nang cao
vu nang » vuc nang, va nang, vu dang
ma hoi » mai hoi, xa hoi, ma hoa

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