Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
hieu vien » hieu hien, hieu viec, thieu nien
cac toc » cac toi, cac nuoc, cac thoi
te sach » toc sach
ky lang » ky dang, ky tang, tay lang
cac tuc » cac tu, cac tac, cac nuoc
va dau » va dao
dau vi » dau ve, dau va, dat vi
vi cua » vai cua, di cua

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

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