Perhaps you should try some spelling variations:
tham soc » cham soc, tham nuoc, ham so
thai son » thai den, thai do, thai hoc
ban hanh » ban hang
ky tang » ky nang, ky dang, kho tang
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, cua triet
te cac » tu cac, ve cac, te cao
di cua » dai cua, doi cua, de cua

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: te cac ky tang ((ha noi) OR (xa hoi)). hieu qua ((tham soc) OR (thai son)) ban hanh di cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te cac ky tang ((ha noi) or (xa hoi)). hieu qua ((tham soc) OR (thai son)) ban hanh di cua tre~".
• Adding a wildcard symbol may retrieve word variants: te cac ky tang ((ha noi) or (xa hoi)). hieu qua ((tham soc) OR (thai son)) ban hanh di cua tre*.