Perhaps you should try some spelling variations:
hang tai » hang va, dung tai
sach ky » sach y, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va, hieu van
ve cham » va cham, ve chat, vu cham
sac ky » cac ky, sai ky
soc va » hoc va, loc va, goc va
doc va » duoc va, hoc va, duc va
tai va » thai va, mai va, tri va
thiet » thieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach ky) or (sac ky)) nang xa hoi. hieu ve cham ((soc va) OR (doc va)) hang tai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sac ky)) nang xa hoi. hieu ve cham ((soc va) OR (doc va)) hang tai va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) or (sac ky)) nang xa hoi. hieu ve cham ((soc va) OR (doc va)) hang tai va thiet".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sac ky)) nang xa hoi. hieu ve cham ((soc va) OR (doc va)) hang tai va thiet*.