Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
ha thanh » va thanh, pham thanh, phan thanh
xa thanh » va thanh, ta thanh, gia thanh
cac tuc » cac toc, cac tu, cac tac
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
y nang » ky nang, ly nang, v nang
ve cac » va cac, vien cac
o hoc » co hoc, mo hoc, so hoc
o hoi » co hoi, o hai, o hoa
vi su » va su, ve su, ki su

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