Perhaps you should try some spelling variations:
ban hanh » ban hang
dau tren » dau tien, dat tren, dau tieng
su sach » so sach, vu sach
sach tu » sach thu, cach tu, sach ty
tu nang » tru nang, tu nong, tu nano
nang xa » nang x, lang xa, nang ma
van cau » van dau, van chat, toan cau
van hau » van ha, van hai, van dau
duc ban » duc tan, duc van, dua ban
cua tre » cua te, cuu tre, cua triet

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