Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
van hanh » van thanh, van anh, van ban
ban hanh » ban hang
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
nam tuc » nam thuc, nam truc, nam tu
tai cua » thai cua, tai cuc, tri cua
va nam » van nam, ha nam, va nay
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((hoc sach) or (dac sac)) ky nang xa hoi. hieu va nam tuc ((van hanh) OR (ban hanh)) tai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc sach) OR (dac sac)) ky nang xa hoi. hieu va nam tuc ((van hanh) OR (ban hanh)) tai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc sach) or (dac sac)) ky nang xa hoi. hieu va nam tuc ((van hanh) OR (ban hanh)) tai cua te".
• Adding a wildcard symbol may retrieve word variants: ((hoc sach) or (dac sac)) ky nang xa hoi. hieu va nam tuc ((van hanh) OR (ban hanh)) tai cua te*.