Perhaps you should try some spelling variations:
sach tham » sach nha
tham tang » nham tang, thai tang, tham lang
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
dang hai » dang khai, hang hai, dung hai
cua tre » cua te, cuu tre, cua triet
so viet » hoc viet
van cam » van nam, van lam, van cau
tang xa » trang xa, tang ma, lang xa
bac va » ban va, bac ha, bao va

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach tham tang xa hoi. hieu van cam ((bac va) or (duc va)) dang hai ((cua tre) or (so viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach tham tang xa hoi. hieu van cam ((bac va) OR (duc va)) dang hai ((cua tre) OR (so viet)).
• Adding a wildcard symbol may retrieve word variants: thu sach tham tang xa hoi. hieu van cam ((bac va) or (duc va)) dang hai ((cua tre) or (so viet))*.