Perhaps you should try some spelling variations:
cam quoc » cac quoc, cao quoc, nam quoc
hanh hai » thanh hai, nhanh hai, hang hai
ban hanh » ban hang
hieu van » hieu va, thien van, lieu va
quoc ban » quoc bao, quoc lan, quoc quan
cuu tre » cau tren, cau treo
van cam » van nam, van lam, van cau
sach ky » sach y, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cua triet, dua tren
sac ky » cac ky, sai ky

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