Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
van hanh » van thanh, ban hanh, van anh
cua tre » cua te, cua triet, dua tren
van cac » van hac, van cau, van bac
sach ly » sach y, sach lo, sach ty
vu sach » vu bach, su sach, vu khach
dai hoi » dai hoc, dai hai, dai moi
mai hoi » mai khoi, lai hoi, mai doi
cuu tre » cau tren, cau treo
cac tu » cac thu, cach tu, cac du
tu van » tu va
ly van » le van, ly va, ly von

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ly van ((mai hoi) or (dai hoi)). hieu van cac tu van hanh vi ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ly van ((mai hoi) OR (dai hoi)). hieu van cac tu van hanh vi ((cua tre) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: vu sach ly van ((mai hoi) or (dai hoi)). hieu van cac tu van hanh vi ((cua tre) or (cuu tre))*.