Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
dau tren » dau tien, dat tren, dau tieng
toc sac » toc sach, toc san, hoc sach
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
thuc va » thuc vat, thuc dan, thuc day
dan vai » dan va, dan tai, dan vat
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky
va dan » ca dan, va dao, va dau

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

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