Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
cua triet » cua viet, su triet, va triet
hieu van » hieu va, thien van, lieu va
hoc sach » hoc sinh, hoc cac, hoc anh
va thanh » gia thanh, va tinh, le thanh
su sach » so sach, vu sach
van cac » van hac, van cau, van bac
cac toc » cac toi, cac nuoc, cac thoi
di cua » dai cua, doi cua, de cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) or (hoc sach)) ky nang x ho. hieu van cac toc ((va thanh) OR (ban thanh)) di cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (hoc sach)) ky nang x ho. hieu van cac toc ((va thanh) OR (ban thanh)) di cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (hoc sach)) ky nang x ho. hieu van cac toc ((va thanh) OR (ban thanh)) di cua triet".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (hoc sach)) ky nang x ho. hieu van cac toc ((va thanh) OR (ban thanh)) di cua triet*.