Perhaps you should try some spelling variations:
hoc viet » hoc hien
tu sach » thu sach, su sach, te sach
vu khac » vu kham, vu khanh, bui khac
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va, hieu van
ve cham » va cham, ve chat, vu cham
soc van » hoc van, oc van, soc dan
sac van » cac van, san van, sat van
vi hoc » li hoc, va hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (vu khac)) ky nang xa hoi. hieu ve cham ((soc van) OR (sac van)) hanh vi hoc viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (vu khac)) ky nang xa hoi. hieu ve cham ((soc van) OR (sac van)) hanh vi hoc viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (vu khac)) ky nang xa hoi. hieu ve cham ((soc van) OR (sac van)) hanh vi hoc viet*".