Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
giau cua » gian cua, gia cua, dieu cua
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
cao hoi » cau hoi, cao hoc, tao hoi
hieu va » lieu va, hieu qua
via cua » gia cua, gian cua, rija cua
co hoi » co hoc, co loi
va bao » va bai
bao bo » bac bo, ban bo, nao bo
bo van » vo van, so van, do van

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 ((cao hoi) or (co hoi)). hieu va bao bo van hanh ((via cua) OR (giau cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((cao hoi) OR (co hoi)). hieu va bao bo van hanh ((via cua) OR (giau cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang ((cao hoi) or (co hoi)). hieu va bao bo van hanh ((via cua) OR (giau cua)) tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((cao hoi) or (co hoi)). hieu va bao bo van hanh ((via cua) OR (giau cua)) tre*.