Perhaps you should try some spelling variations:
quoc lan » quoc ban, nuoc luan, quoc quan
cac quoc » cac nuoc, cac cuoc, cao quoc
te sach » toc sach
tai cua » thai cua, tai cuc, tri cua
han tai » hang tai, nhan tai, van tai
lan han » luan han, van han, lan dan
qua cac » cua cac
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
tang ma » mang may, tang van
nang ma » sang ma, nang cao, mang may
nang xa » nang x, lang xa, mang xa

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky ((nang xa) or (((nang ma) OR (tang ma)))) hoi. hieu qua cac quoc lan han tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky ((nang xa) OR (((nang ma) OR (tang ma)))) hoi. hieu qua cac quoc lan han tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky ((nang xa) or (((nang ma) OR (tang ma)))) hoi. hieu qua cac quoc lan han tai cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ky ((nang xa) or (((nang ma) OR (tang ma)))) hoi. hieu qua cac quoc lan han tai cua tre*.