Perhaps you should try some spelling variations:
day thanh » dao thanh, dat thanh, da thanh
hieu van » hieu va, thien van, lieu va
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
thuc day » thuc dan, thuc vat
dinh cu » dinh cuu, dinh chuc, dinh chau
y nang » ky nang, ly nang, v nang
vi cuu » vi luu, vinh cuu

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) y nang x ho. hieu van nam thuc day thanh ((vi cuu) OR (dinh cu)) tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) y nang x ho. hieu van nam thuc day thanh ((vi cuu) or (dinh cu)) tre~".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) y nang x ho. hieu van nam thuc day thanh ((vi cuu) or (dinh cu)) tre*.