Perhaps you should try some spelling variations:
cham duc » pham duc, cham soc, phan duc
toan tai » toan tap, doanh tai, toan ban
pham duy » pham duc
tai cua » thai cua, tai cuc, tri cua
va toan » van toan, bai toan, tap toan
tu sach » thu sach, su sach, te sach
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
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: ((tu sach) or (hoc sinh)) ky lang xa hoi. lieu va ((cham duc) OR (pham duy)) va toan tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (hoc sinh)) ky lang xa hoi. lieu va ((cham duc) OR (pham duy)) va toan tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (hoc sinh)) ky lang xa hoi. lieu va ((cham duc) OR (pham duy)) va toan tai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (hoc sinh)) ky lang xa hoi. lieu va ((cham duc) OR (pham duy)) va toan tai cua tre*.