Perhaps you should try some spelling variations:
hanh thai » nhanh thai, hinh thai, hanh tai
thai cua » than cua, tai cuc, tri cua
van hanh » van thanh, ban hanh, van anh
cac duc » cao duc, cac dac, cac nuoc
sach ky » sac ky, sach ty, sach kem
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
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: te ((sach ky) or (sach y)) nang o hoi. hieu ve ((cac duc) OR (cac du)) van hanh thai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ky) OR (sach y)) nang o hoi. hieu ve ((cac duc) OR (cac du)) van hanh thai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ky) or (sach y)) nang o hoi. hieu ve ((cac duc) OR (cac du)) van hanh thai cua tre".
• Adding a wildcard symbol may retrieve word variants: te ((sach ky) or (sach y)) nang o hoi. hieu ve ((cac duc) OR (cac du)) van hanh thai cua tre*.