Perhaps you should try some spelling variations:
dung sai » dung tai, dung va, dung dat
danh sai » danh bat, danh dau, hanh san
thu sac » thu sach, thu san, thu xac
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky
cac lo » cac lop, cac co, cac ho
nang o » nang co, nang ho, nang ro
cac bo » bac bo, cac co
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sac ky nang o hoi. hieu qua ((cac lo) OR (cac bo)) va ((danh sai) or (dung sai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sac ky nang o hoi. hieu qua ((cac lo) OR (cac bo)) va ((danh sai) OR (dung sai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sac ky nang o hoi. hieu qua ((cac lo) OR (cac bo)) va ((danh sai) or (dung sai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sac ky nang o hoi. hieu qua ((cac lo) OR (cac bo)) va ((danh sai) or (dung sai)) cua tre*.