Perhaps you should try some spelling variations:
ban hanh » ban hang
cua viet » ca viet, hoa viet, cua vat
hieu ve » hieu va, hieu van
sac ky » cac ky, sai ky
ve cac » va cac, vien cac
cac so » cac co, cac bo, cac ho
so ban » sao ban, so bang, co ban
vi cua » vai cua, di cua
x hoi » xa hoi, o hoi, x ho

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 y) or (sac ky)) nang x hoi. hieu ve cac so ban hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach y) OR (sac ky)) nang x hoi. hieu ve cac so ban hanh vi cua viet.
• Adding a wildcard symbol may retrieve word variants: tu ((sach y) or (sac ky)) nang x hoi. hieu ve cac so ban hanh vi cua viet*.