Perhaps you should try some spelling variations:
cau thuc » cau truc, cuu thuc, can thuc
vat hanh » vat thanh, van hanh, va hanh
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va
hanh va » hang va, hanh vi
su tien » su kien, su hien, tu tieng
sai ky » sac ky
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 ty) or (sai ky)) nang ma hoi. ((hieu va) OR (hieu qua)) cau thuc vat hanh va su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sai ky)) nang ma hoi. ((hieu va) OR (hieu qua)) cau thuc vat hanh va su tien*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) or (sai ky)) nang ma hoi. ((hieu va) OR (hieu qua)) cau thuc vat hanh va su tien*".