Perhaps you should try some spelling variations:
cam quoc » cac quoc, cao quoc, nam quoc
san benh » sau benh, so benh, gay benh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
va cam » va cham, va cac, va cao

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 xa hoi. lieu va cam quoc ((san benh) OR (tai benh)) ve ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang xa hoi. lieu va cam quoc ((san benh) OR (tai benh)) ve ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang xa hoi. lieu va cam quoc ((san benh) OR (tai benh)) ve ((cua tre) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang xa hoi. lieu va cam quoc ((san benh) OR (tai benh)) ve ((cua tre) or (cuu tre))*.