Perhaps you should try some spelling variations:
dua tren » dung tren
van hanh » van thanh, ban hanh, van anh
sach ty » sach tu, sach thu, xach tay
duc van » duc va, duc tan, duc manh
cao duc » dao duc, cao suc, giao duc
cuu tre » cua tre, cau tren, cau treo
hieu ve » hieu va, hieu van
tang xa » trang xa, tang ma, lang xa
ve cao » va cao, ve bao, ve cac

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 y)) tang xa hoi. hieu ve cao duc van hanh vi ((dua tren) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ty) OR (sach y)) tang xa hoi. hieu ve cao duc van hanh vi ((dua tren) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: te ((sach ty) or (sach y)) tang xa hoi. hieu ve cao duc van hanh vi ((dua tren) or (cuu tre))*.