Perhaps you should try some spelling variations:
chat thuc » thuat thuc, nhan thuc, chat thai
thu sach » thuat sach, thuoc sach, thu hoach
thu hang » thi hang, thuc hanh, thu huong
hang cau » hang dau, hang ca, nhung cau
hieu cao » chieu cao, hieu cac, hieu ca
hanh dai » hanh tai, hanh dao, vanh dai
va hanh » van hanh, va thanh, ban hanh
tu sach » su sach, te sach, tu cach
so viet » hoc viet
thuc va » thuc vat, thuc dan, thuc day

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) OR (thu sach)) thu hang cau hoi. hieu cao chat thuc va hanh dai ((su viet) or (so viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) thu hang cau hoi. hieu cao chat thuc va hanh dai ((su viet) OR (so viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) thu hang cau hoi. hieu cao chat thuc va hanh dai ((su viet) or (so viet))".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) thu hang cau hoi. hieu cao chat thuc va hanh dai ((su viet) or (so viet))*.