Perhaps you should try some spelling variations:
xa thanh » va thanh, ha thanh, ta thanh
thanh ki » thanh kim, thanh ky, thanh ke
su triet » su viet, su tien, ve triet
sach ty » sach tu, sach thu, xach tay
hieu ve » hieu va, hieu van
cac tac » cac toc, cac bac, cac dac
nang o » nang co, nang ho, nang ro
ve cac » va cac, vien cac
tac xa » tuc xa, tac da
o hoi » co hoi, o hoc, o hai
ki su » ky 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) or (sach y)) nang o hoi. hieu ve cac tac xa thanh ki su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach y)) nang o hoi. hieu ve cac tac xa thanh ki su triet.
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) or (sach y)) nang o hoi. hieu ve cac tac xa thanh ki su triet*.