Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
thu sach » thuat sach, thuoc sach, thu hoach
hieu van » thien van, lieu va, hieu ve
tu sach » su sach, te sach, tu cach
hieu va » lieu va, hieu qua
hanh ve » hanh vi, hanh va, hanh kem
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
ca viet » va viet, co viet, hoa viet
lo nang » ho nang, ly nang, loai nang
x hoi » xa hoi, o hoi, x ho
ve ca » ve cac, ve cai, ve cau

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) lo nang x hoi. ((hieu van) OR (hieu va)) nam thuc va hanh ve ca viet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) lo nang x hoi. ((hieu van) or (hieu va)) nam thuc va hanh ve ca viet~".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) lo nang x hoi. ((hieu van) or (hieu va)) nam thuc va hanh ve ca viet*.