Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
toc sach » hoc sach, doc sach, nuoc sach
san benh » sau benh, tai benh, so benh
quoc san » quoc sang, nuoc san, quoc ban
va chat » van chat, va phat, cao chat
benh vi » benh va, benh ve, benh li
cua tre » cua te, cuu tre, cua triet
va cham » va tham
lang xa » lang ha, dang xay, lang van
y lang » o lang, _ lang, tay lang
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 (thuoc sach)) y lang xa hoi. hieu ((va cham) OR (va chat)) quoc san benh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (thuoc sach)) y lang xa hoi. hieu ((va cham) OR (va chat)) quoc san benh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (thuoc sach)) y lang xa hoi. hieu ((va cham) OR (va chat)) quoc san benh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (thuoc sach)) y lang xa hoi. hieu ((va cham) OR (va chat)) quoc san benh vi cua tre*.