Perhaps you should try some spelling variations:
san thanh » ban thanh, van thanh, son thanh
hieu vien » hieu hien, hieu viec, thieu nien
ve triet » va trien, su triet
san hanh » ban hanh, van hanh, dan hanh
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
sach ky » sac ky, sach y, sach ty
cac toc » cac toi, cac thoi
nang xa » nang x, lang xa, nang ma
vu sach » vu bach, su sach, vu khach
vi ve » va ve, gi ve, ve ve

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 vien ((cac toc) or (cac nuoc)) ((san hanh) OR (san thanh)) vi ve triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky nang xa hoi. hieu vien ((cac toc) OR (cac nuoc)) ((san hanh) OR (san thanh)) vi ve triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky nang xa hoi. hieu vien ((cac toc) or (cac nuoc)) ((san hanh) OR (san thanh)) vi ve triet".
• Adding a wildcard symbol may retrieve word variants: vu sach ky nang xa hoi. hieu vien ((cac toc) or (cac nuoc)) ((san hanh) OR (san thanh)) vi ve triet*.