Perhaps you should try some spelling variations:
cac quoc » cac nuoc, cac cuoc, han quoc
hanh tai » thanh tai, hang tai, han tai
lan hanh » ban hanh, van hanh, lan anh
cao quoc » cao thuoc, han quoc, cua quoc
tai cua » thai cua, tai cuc, tri cua
te sach » toc sach
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
cua tre » cua te, cuu tre, cua triet

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