Perhaps you should try some spelling variations:
xa thanh » va thanh, ha thanh, ta thanh
thanh vi » hanh vi, thanh va, thanh ve
su triet » su viet, su tien, ve triet
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
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
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 ty xang ((o hoi) or (o hoc)). hieu ve cac tac xa thanh vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty xang ((o hoi) OR (o hoc)). hieu ve cac tac xa thanh vi su triet.
• Adding a wildcard symbol may retrieve word variants: tu sach ty xang ((o hoi) or (o hoc)). hieu ve cac tac xa thanh vi su triet*.