Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
hanh dai » hanh tai, hanh dao, vanh dai
sach ty » sach tu, sach thu, xach tay
tang ma » mang may, tang van
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
su viet » so viet
ma hoi » mai hoi, xa hoi, ma hoa
va nam » van nam, ha nam, va nay
dai su » dai sua, dai so, dan su

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 y) or (sach ty)) tang ma hoi. lieu va nam thuc va hanh dai su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach y) OR (sach ty)) tang ma hoi. lieu va nam thuc va hanh dai su viet.
• Adding a wildcard symbol may retrieve word variants: tu ((sach y) or (sach ty)) tang ma hoi. lieu va nam thuc va hanh dai su viet*.