Perhaps you should try some spelling variations:
day hanh » day nhanh, day thanh, dao hanh
thuc day » thuc dan, thuc vat
nam thuc » nam thuoc, am thuc, nam thu
sang mai » sang ma, sang tai, lang mai
hieu van » hieu va, thien van, lieu va
so sach » so sanh, bo sach, hoc sach
hieu ve » hieu va
mai hoi » mai khoi, dai hoi, lai hoi
ky sang » ky nang, ky dang, ky tang
co sach » bo sach, cuon sach, hoc sach
ca viet » va viet, co viet, hoa viet
vi ca » vit ca, li ca, va ca

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

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