Perhaps you should try some spelling variations:
hanh thai » nhanh thai, hinh thai, hanh tai
chat duc » chat xuc, chet duoc, pham duc
thai cua » than cua, tai cuc, tri cua
tan hanh » tan thanh, tang hanh, toan hanh
chat doc » chat hoc, chau doc, thuat doc
hieu van » hieu va, thien van, lieu va
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach ty, sach kem
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 van ((chat duc) OR (chat doc)) tan 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 van ((chat duc) OR (chat doc)) tan 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 van ((chat duc) OR (chat doc)) tan hanh thai cua tre*".