Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
thu sach » tu sach, thuat sach, thuoc sach
ta thanh » tai thanh, va thanh, ha thanh
xa thanh » va thanh, ha thanh, gia thanh
cac tac » cac toc, cac bac, cac dac
te sach » toc sach
ty nang » ky nang, ty xang, ty hang
hieu ve » hieu va, hieu van
ve cac » va cac, vien cac
nang o » nang co, nang ho, nang ro
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: ((te sach) or (thu sach)) ty nang o hoi. hieu ve cac tac ((xa thanh) OR (ta thanh)) va su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (thu sach)) ty nang o hoi. hieu ve cac tac ((xa thanh) OR (ta thanh)) va su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (thu sach)) ty nang o hoi. hieu ve cac tac ((xa thanh) OR (ta thanh)) va su triet".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (thu sach)) ty nang o hoi. hieu ve cac tac ((xa thanh) OR (ta thanh)) va su triet*.