Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
nay quoc » nam quoc, nhap quoc, nhan quoc
sau benh » san benh, phau benh, tai benh
quoc sau » quoc su, quoc suu, quoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
hieu va » lieu va, hieu qua
benh vi » benh va, benh ve, benh li
cua tre » cua te, cuu tre, cua triet
c song » _ song, k song, cua song
va nay » va ngay, va cay
y song » _ song, k song, hay song
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: ((toc sach) or (hoc sach)) ((y song) or (c song)) xa hoi. hieu va nay quoc sau benh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) ((y song) OR (c song)) xa hoi. hieu va nay quoc sau benh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (hoc sach)) ((y song) or (c song)) xa hoi. hieu va nay quoc sau benh vi cua tre*.