Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
van hanh » van thanh, ban hanh, van anh
duc van » duc va, duc tan, duc manh
cac duc » cac du, cao duc, cac dac
van cac » van hac, van cau, van bac
sach ty » sach y, sach tu, sach thu
te sach » toc sach
lang xa » lang ha, dang xay, lang van
nang xa » nang x, nang ma, mang xa
cua cu » cua chu, cua cau, cua co
cua su » qua 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 ((nang xa) OR (lang xa)) hoi. hieu van cac duc van hanh vi ((cua cu) or (cua su))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty ((nang xa) OR (lang xa)) hoi. hieu van cac duc van hanh vi ((cua cu) OR (cua su)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty ((nang xa) OR (lang xa)) hoi. hieu van cac duc van hanh vi ((cua cu) or (cua su))".
• Adding a wildcard symbol may retrieve word variants: te sach ty ((nang xa) OR (lang xa)) hoi. hieu van cac duc van hanh vi ((cua cu) or (cua su))*.