Perhaps you should try some spelling variations:
quoc ban » quoc bao, quoc lan, quoc quan
cam quoc » cac quoc, cao quoc, nam quoc
tu sach » thu sach, su sach, te sach
cua tre » cuu tre, cua triet, dua tren
ban anh » ban hanh, ban banh, ban danh
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
ty nang » ky nang, ty xang, ty hang
va cam » va cham, va cac, va cao
cua te » cua tu
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 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 ty nang ((x hoi) or (o hoi)). hieu va cam quoc ban anh d ((cua tre) OR (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang ((x hoi) OR (o hoi)). hieu va cam quoc ban anh d ((cua tre) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang ((x hoi) or (o hoi)). hieu va cam quoc ban anh d ((cua tre) OR (cua te))".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang ((x hoi) or (o hoi)). hieu va cam quoc ban anh d ((cua tre) OR (cua te))*.