Perhaps you should try some spelling variations:
ban hanh » ban hang
tuc ban » thuc ban, truc ban, tu ban
su sach » so sach, vu sach
hieu ve » hieu va, hieu van
ky danh » ky anh, ky dang
cac tuc » cac toc, cac tu, cac tac
ve cac » va cac, vien cac
vai va » mai va, hai va, lai va
dai va » mai va

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 ((ky nang) or (ky danh)) xa hoi. hieu ve cac tuc ban hanh ((vai va) OR (dai va)) trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ky nang) OR (ky danh)) xa hoi. hieu ve cac tuc ban hanh ((vai va) OR (dai va)) trien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ky nang) or (ky danh)) xa hoi. hieu ve cac tuc ban hanh ((vai va) OR (dai va)) trien".
• Adding a wildcard symbol may retrieve word variants: su sach ((ky nang) or (ky danh)) xa hoi. hieu ve cac tuc ban hanh ((vai va) OR (dai va)) trien*.