Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
cau tren » cu tren, dau tren, ca tren
thanh vi » hanh vi, thanh va, thanh ve
hieu van » thien van, lieu va, hieu ve
sach tu » sach thu, cach tu, sach ty
cua tre » cua te, cuu tre, cua triet
duc ban » duc tan, duc van, dua ban
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
tu nang » tru nang, tu nong, tu nano
cau duc » cao duc, cau luc, chu duc

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach tu nang xa hoi. ((hieu van) OR (hieu va)) cau duc ban thanh vi ((cua tre) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach tu nang xa hoi. ((hieu van) OR (hieu va)) cau duc ban thanh vi ((cua tre) OR (cau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach tu nang xa hoi. ((hieu van) OR (hieu va)) cau duc ban thanh vi ((cua tre) or (cau tren))".
• Adding a wildcard symbol may retrieve word variants: su sach tu nang xa hoi. ((hieu van) OR (hieu va)) cau duc ban thanh vi ((cua tre) or (cau tren))*.