Perhaps you should try some spelling variations:
thuat sac » thuat sach, thuat san, thuat tac
hieu van » hieu va, thien van, lieu va
van chat » cao chat
chat soc » cham soc, chat hoc, chat doc
van tuan » van quan, van ban, anh tuan
vinh cua » sinh cua, tinh cua, dinh cua
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky
co hoi » co hoc, co loi
o hoi » o hoc, o hai, o hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat sac ky nang ((o hoi) OR (co hoi)). hieu van chat soc ((van minh) or (van tuan)) vinh cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sac ky nang ((o hoi) OR (co hoi)). hieu van chat soc ((van minh) OR (van tuan)) vinh cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sac ky nang ((o hoi) OR (co hoi)). hieu van chat soc ((van minh) or (van tuan)) vinh cua tre".
• Adding a wildcard symbol may retrieve word variants: thuat sac ky nang ((o hoi) OR (co hoi)). hieu van chat soc ((van minh) or (van tuan)) vinh cua tre*.