Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
cua viet » ca viet, hoa viet, cua vat
hanh dai » hanh tai, hanh dao, vanh dai
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
su sach » so sach, vu sach
ky dang » ky nang, ky danh
ky sang » ky nang, ky tang, duy sang
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: ((su sach) or (thuoc sach)) ((ky sang) OR (ky dang)) ma hoi. hieu van nam thuc va hanh dai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (thuoc sach)) ((ky sang) OR (ky dang)) ma hoi. hieu van nam thuc va hanh dai cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (thuoc sach)) ((ky sang) OR (ky dang)) ma hoi. hieu van nam thuc va hanh dai cua viet".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (thuoc sach)) ((ky sang) OR (ky dang)) ma hoi. hieu van nam thuc va hanh dai cua viet*.