Perhaps you should try some spelling variations:
dam thuc » am thuc, dan thuc, nam thuc
cua viet » ca viet, cua vat, cua dieu
sang mai » sang ma, sang tai, lang mai
van hanh » van thanh, ban hanh, van anh
hieu van » hieu va, thien van, lieu va
sach ky » sac ky, sach y, sach ty
su sach » so sach, vu sach
mai hoi » mai khoi, dai hoi, lai hoi
ky sang » ky nang, ky dang, ky tang
cam tu » cam thu, nam tu, dam tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky sang mai hoi. hieu van ((dam thuc) or (cam tu)) van hanh vi ((cua viet) or (hoa viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky sang mai hoi. hieu van ((dam thuc) OR (cam tu)) van hanh vi ((cua viet) OR (hoa viet)).
• Adding a wildcard symbol may retrieve word variants: su sach ky sang mai hoi. hieu van ((dam thuc) or (cam tu)) van hanh vi ((cua viet) or (hoa viet))*.