Perhaps you should try some spelling variations:
ban thanh » ban hang
hieu viec » nhieu viec, hieu ve, sieu viet
cua triet » cua viet, su triet, va triet
viec cac » vien cac, viec cua, viec lam
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
ban hanh » ban hang
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
ty hang » ly hang, ty xang, thi hang
vai cua » dai cua, hai cua, lai cua
hang o » hang do, hang o2, hoang o
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: tu sach ty hang o hoi. hieu viec cac nuoc ((ban hanh) or (ban thanh)) vai cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty hang o hoi. hieu viec cac nuoc ((ban hanh) OR (ban thanh)) vai cua triet.
• Adding a wildcard symbol may retrieve word variants: tu sach ty hang o hoi. hieu viec cac nuoc ((ban hanh) or (ban thanh)) vai cua triet*.