Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
hac truc » hoc truc, hang truc, sach truc
cua tre » cua te, cuu tre, cua triet
dinh vi » dinh ve, dinh viet, dinh tri
sach ty » sach y, sach tu, sach thu
tu sach » thu sach, su sach, te sach
ty nang » ky nang, ty xang, ty hang
hieu va » lieu va, hieu qua
truc va » thuc va, thuc vat, trung va
va hac » van hac, va khac, va cac
nang o » nang co, nang ho, nang ro
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 ty nang o hoi. hieu va hac truc va ((hanh vi) or (dinh vi)) ((cua tre) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang o hoi. hieu va hac truc va ((hanh vi) OR (dinh vi)) ((cua tre) OR (cau tren)).
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang o hoi. hieu va hac truc va ((hanh vi) or (dinh vi)) ((cua tre) or (cau tren))*.