Perhaps you should try some spelling variations:
hinh thai » sinh thai, tinh thai, dinh thi
hanh thai » nhanh thai, hanh tai, anh thai
duc manh » suc manh, duc anh, duc minh
hieu van » hieu va, thien van, lieu va
cac duc » cac du, cao duc, cac dac
van cac » van hac, van cau, van bac
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 cac duc manh ((hanh thai) OR (hinh 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 cac duc manh ((hanh thai) OR (hinh 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 cac duc manh ((hanh thai) OR (hinh thai)) cua tre*".