Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va
cac duc » cac du, cao duc, cac dac
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
cua tu » cua tuc, cua su, cua cu

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