Perhaps you should try some spelling variations:
vua triet » cua triet, va triet, va trien
hieu van » hieu va, thien van, lieu va
sach ky » sach y, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
van dau » van dao, phan dau
duoc va » duc va, duoc ma, duong va
hanh va » hang va, hanh vi
sac ky » cac ky, sai ky

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

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