Perhaps you should try some spelling variations:
cau theo » cau thi, cau tao
tu sach » thu sach, su sach, te sach
qua cac » cua cac
cac tac » cac toc, cac bac, cac dac
van vat » van chat, nhan vat
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
y nang » ky nang, ly nang, v nang
nang o » nang co, nang ho, nang ro
tac va » tac da, tac xa, tuc va
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: tu sach y nang o hoi. hieu qua cac tac va van vat ((cua tre) or (((cuu tre) or (cau theo))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang o hoi. hieu qua cac tac va van vat ((cua tre) OR (((cuu tre) OR (cau theo)))).
• Adding a wildcard symbol may retrieve word variants: tu sach y nang o hoi. hieu qua cac tac va van vat ((cua tre) or (((cuu tre) or (cau theo))))*.