Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
va thanh » gia thanh, ban thanh, va tinh
hieu van » thien van, lieu va, hieu ve
sach ty » sach y, sach thu, xach tay
dai cuu » dai cua, dai huu
hieu va » lieu va, hieu qua
sach tu » sach thu, cach tu, sach uu
cuu tre » cua tre, cau tren, cau treo
hang x » nang x, hoang xa, chang xu
x hoi » xa hoi, o hoi, x ho
du va » dau va, tu va, su va

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

• Performing a fuzzy search may retrieve terms with similar spellings: te ((sach ty) or (sach tu)) hang x hoi. ((hieu van) OR (hieu va)) cac du va thanh dai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ty) OR (sach tu)) hang x hoi. ((hieu van) OR (hieu va)) cac du va thanh dai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ty) or (sach tu)) hang x hoi. ((hieu van) OR (hieu va)) cac du va thanh dai cuu tre".
• Adding a wildcard symbol may retrieve word variants: te ((sach ty) or (sach tu)) hang x hoi. ((hieu van) OR (hieu va)) cac du va thanh dai cuu tre*.