Perhaps you should try some spelling variations:
hanh vai » hanh vi, hanh va, hanh tai
tu sach » thu sach, te sach, tu cach
vai cua » dai cua, hai cua, lai cua
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
su sach » so sach, vu sach
nang o » nang co, nang ho, nang ro
tuc va » thuc va, truc va, duc va
ve cam » ve cham, ve cac, va cam
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) or (su sach)) ky nang o hoi. hieu ve cam ((tuc va) OR (tuc xa)) hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky nang o hoi. hieu ve cam ((tuc va) OR (tuc xa)) hanh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ky nang o hoi. hieu ve cam ((tuc va) OR (tuc xa)) hanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky nang o hoi. hieu ve cam ((tuc va) OR (tuc xa)) hanh vai cua tre*.