Perhaps you should try some spelling variations:
khoa hoi » khoan hoi, khoa hoc, khoa doi
van hanh » van thanh, ban hanh, van anh
tuc van » thuc van, truc van, tuc va
cam tuc » cam xuc, cam tu, nam thuc
hieu ve » hieu va, hieu van
su viet » so viet
hoa hoi » hoa hoc, hoa doi, hoc hoi
sac ky » cac ky
ve cam » ve cham, ve cac, va cam
vi su » va su, ve su, ki su

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sac ky) or (sai ky)) nang ((hoa hoi) OR (khoa hoi)). hieu ve cam tuc van hanh vi su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sac ky) OR (sai ky)) nang ((hoa hoi) OR (khoa hoi)). hieu ve cam tuc van hanh vi su viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sac ky) or (sai ky)) nang ((hoa hoi) OR (khoa hoi)). hieu ve cam tuc van hanh vi su viet*".