Perhaps you should try some spelling variations:
hanh dai » hanh tai, hanh dao, vanh dai
nam thuc » nam thuoc, am thuc, nam thu
sach ky » sac ky, sach y, sach kem
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
hieu va » lieu va, hieu qua
su viet » so viet
sach ty » sach y, sach tu, sach thu
ma hoi » mai hoi, xa hoi, me hoi
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 ky) or (sach ty)) tang ((ma hoi) OR (ma hoa)). hieu va nam thuc va hanh dai su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach ty)) tang ((ma hoi) OR (ma hoa)). hieu va nam thuc va hanh dai su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (sach ty)) tang ((ma hoi) OR (ma hoa)). hieu va nam thuc va hanh dai su viet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sach ty)) tang ((ma hoi) OR (ma hoa)). hieu va nam thuc va hanh dai su viet*.