Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
thanh ha » thanh hoa, thanh hai, nhanh ha
thanh va » thanh van, hanh va, thanh ve
cac tuc » cac toc, cac tu, cac tac
tu sach » thu sach, su sach, te sach
ty nang » ky nang, ty hang, ly nang
hieu ve » hieu va, hieu van
ve cac » va cac, vien cac
o hoi » co hoi, o hoc, o hai

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