Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
ban hanh » ban hang
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
van cam » van nam, van lam, van cau
va danh » va dinh, va dan, va hanh
su viet » so viet
cam tu » cam thu, nam tu, dam tu
x hoi » xa hoi, o hoi, x ho
ki su » ky su

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky nang x hoi. hieu van cam tu ((ban hanh) or (va danh)) ki su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky nang x hoi. hieu van cam tu ((ban hanh) OR (va danh)) ki su viet.
• Adding a wildcard symbol may retrieve word variants: vu sach ky nang x hoi. hieu van cam tu ((ban hanh) or (va danh)) ki su viet*.