Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
thanh ve » hanh ve, thanh va, thanh vien
thanh vi » hanh vi, thanh va, nhanh vi
viet cac » vien cac, viet ca, viet bac
su viet » so viet
su sach » so sach, vu sach
tu sach » thu sach, te sach, tu cach
x hoi » xa hoi, o hoi, x ho

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