Perhaps you should try some spelling variations:
sach han » sach tham, sach danh, sach nang
han nang » phan nang, van nang, ban nang
cau thuc » cau truc, cuu thuc, can thuc
dan thuc » dan toc, am thuc
van hanh » van thanh, ban hanh, van anh
cua viet » ca viet, hoa viet, cua dieu
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
ma hoi » mai hoi, xa hoi, ma hoa

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach han nang ma hoi. hieu va ((cau thuc) OR (dan thuc)) van hanh kem ((cua viet) OR (cua vat))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach han nang ma hoi. hieu va ((cau thuc) or (dan thuc)) van hanh kem ((cua viet) OR (cua vat))~".
• Adding a wildcard symbol may retrieve word variants: tu sach han nang ma hoi. hieu va ((cau thuc) or (dan thuc)) van hanh kem ((cua viet) OR (cua vat))*.