Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thanh va » thanh van, hanh va, thanh ha
xa thanh » va thanh, ha thanh, ta thanh
su triet » su viet, su tien, ve triet
thu sach » tu sach, thuat sach, thuoc sach
ty nang » ky nang, ty xang, ty hang
hieu ve » hieu va, hieu van
cac tac » cac toc, cac bac, cac dac
ve cac » va cac, vien cac
tac xa » tuc xa, tac da
o hoi » co hoi, o hai, o hoa
o hoc » co hoc, mo hoc, so hoc

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