Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
tu sach » thu sach, su sach, tu cach
cua tre » cua te, cuu tre, cua triet
te sach » toc sach
nang o » nang co, nang ho, nang ro
ve cac » va cac, vien cac
vi cua » vai cua, di cua
ve cam » ve cham, va cam, ve cai
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 (te sach)) ky nang o hoi. hieu ((ve cam) or (ve cac)) thuc van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) ky nang o hoi. hieu ((ve cam) OR (ve cac)) thuc van hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (te sach)) ky nang o hoi. hieu ((ve cam) or (ve cac)) thuc van hanh vi cua tre*.