Perhaps you should try some spelling variations:
nay quoc » nam quoc, nhap quoc, nhan quoc
sau benh » san benh, phau benh, so benh
te sach » toc sach
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
y song » _ song, k song, hay song
c song » _ song, k song, cua song
va nay » va ngay, va cay
vi cua » vai cua, di cua

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 song) or (c song)) xa hoi. hieu va nay quoc ((sau benh) OR (tai benh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((y song) OR (c song)) xa hoi. hieu va nay quoc ((sau benh) OR (tai benh)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((y song) or (c song)) xa hoi. hieu va nay quoc ((sau benh) OR (tai benh)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ((y song) or (c song)) xa hoi. hieu va nay quoc ((sau benh) OR (tai benh)) vi cua tre*.