Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
van hanh » ban hanh, van anh, van ban
phan duc » pham duc, phan tu, phan dau
van phan » van phong, luan phan, van ban
sach ty » sach y, sach tu, sach thu
cao hoi » cau hoi, co hoi, cao hoc
ty hang » ly hang, ty xang, thi hang
hoi cua » hoi chuc
cua tre » cua te, cuu tre, cua triet
co loi » co hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ty hang ((cao hoi) or (co loi)). hieu van phan duc ((van hanh) OR (van thanh)) hoi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty hang ((cao hoi) OR (co loi)). hieu van phan duc ((van hanh) OR (van thanh)) hoi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty hang ((cao hoi) or (co loi)). hieu van phan duc ((van hanh) OR (van thanh)) hoi cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ty hang ((cao hoi) or (co loi)). hieu van phan duc ((van hanh) OR (van thanh)) hoi cua tre*.