Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
thuc day » thuc dan, thuc vat
day hanh » day nhanh, day thanh, dao hanh
dang xa » dang xay, dang ha, dang va
lang xa » lang ha, dang xay, lang van
cua tre » cua te, cuu tre, cua triet
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky
vi cua » vai cua, di cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky ((dang xa) or (lang xa)) hoi. hieu van nam thuc day hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky ((dang xa) OR (lang xa)) hoi. hieu van nam thuc day hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sac ky ((dang xa) or (lang xa)) hoi. hieu van nam thuc day hanh vi cua tre*.