Perhaps you should try some spelling variations:
xa thanh » va thanh, ha thanh, ta thanh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
cac tuc » cac toc, cac tu, cac tac
nang o » nang co, nang ho, nang ro
ve cac » va cac, vien cac
o hai » co hai, so hai, o lai
ki su » ky su
ve su » va su

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang o hai. hieu ve cac tuc xa thanh ((ki su) OR (ve su)) triet~.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang o hai. hieu ve cac tuc xa thanh ((ki su) or (ve su)) triet*.