Perhaps you should try some spelling variations:
tu tieng » luc tieng, tu tuong, tu trong
vat hanh » vat thanh, van hanh, va hanh
cau thuc » cau truc, cuu thuc, can thuc
su tien » su kien, su hien, dau tien
hanh va » hang va, hanh vi
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
va cau » van cau, va cac, va dau
sai ky » sac ky

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 ty) or (sai ky)) nang ma hoi. hieu va cau thuc vat hanh va ((su tien) OR (tu tieng))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sai ky)) nang ma hoi. hieu va cau thuc vat hanh va ((su tien) OR (tu tieng))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) or (sai ky)) nang ma hoi. hieu va cau thuc vat hanh va ((su tien) OR (tu tieng))*".