Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hieu van » hieu va, thien van, lieu va
duc van » duc va, duc tan, duc manh
cac duc » cac du, cao duc, cac dac
van cac » van hac, van cau, van bac
lang xa » lang ha, dang xay, lang van
sach ty » sach tu, sach thu, xach tay
nang xa » nang x, nang ma, mang xa
vi cua » vai cua, di cua
cua cu » cua chu, cua cau, cua su

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)) ((nang xa) or (lang xa)) hoi. hieu van cac duc van hanh vi cua cu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ty) OR (sach y)) ((nang xa) OR (lang xa)) hoi. hieu van cac duc van hanh vi cua cu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ty) OR (sach y)) ((nang xa) or (lang xa)) hoi. hieu van cac duc van hanh vi cua cu".
• Adding a wildcard symbol may retrieve word variants: te ((sach ty) OR (sach y)) ((nang xa) or (lang xa)) hoi. hieu van cac duc van hanh vi cua cu*.