Perhaps you should try some spelling variations:
tinh doi » trinh doc, trinh do, tinh hoc
te sach » toc sach
cao duc » dao duc, cao suc, giao duc
tinh di » trinh di, tinh da, tin di
cua tre » cua te, cuu tre, cua triet
cac duc » cac du, cac dac, cac nuoc
hieu va » lieu va, hieu qua
y xang » ty xang
xang x » nang x
x hoi » xa hoi, o hoi, x ho

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 xang x hoi. hieu va ((cac duc) OR (cao duc)) va ((tinh di) or (tinh doi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach y xang x hoi. hieu va ((cac duc) OR (cao duc)) va ((tinh di) OR (tinh doi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach y xang x hoi. hieu va ((cac duc) OR (cao duc)) va ((tinh di) or (tinh doi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach y xang x hoi. hieu va ((cac duc) OR (cao duc)) va ((tinh di) or (tinh doi)) cua tre*.