Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cac quoc » cac nuoc, cac cuoc, cao quoc
quoc ban » quoc bao, quoc lan, quoc quan
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
van cac » van hac, van cau, van bac
ban anh » ban hanh, ban banh, ban danh
lai cua » dai cua, hai cua, lai chau
vi cua » vai cua, di cua
x hoi » xa hoi, o hoi, 5 hoi

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 ky nang ((x hoi) OR (x ho)). hieu van cac quoc ban anh ((vi cua) or (lai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((x hoi) OR (x ho)). hieu van cac quoc ban anh ((vi cua) OR (lai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((x hoi) OR (x ho)). hieu van cac quoc ban anh ((vi cua) or (lai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((x hoi) OR (x ho)). hieu van cac quoc ban anh ((vi cua) or (lai cua)) tre*.