Perhaps you should try some spelling variations:
day doanh » vay doanh, dao doanh, day danh
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
thuc dan » thuc hanh, hoc dan, thuc vat
thuc day » thuc vat
thuc va » thuc vat
tu sach » thu sach, te sach, tu cach
hang xa » hoang xa, hang va, hang ca
ty hang » ly hang, ty xang, thi hang
su sach » so sach, vu sach

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: ((tu sach) OR (su sach)) ty hang xa hoi. hieu van nam thuc day doanh ((thuc va) OR (thuc dan)) te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ty hang xa hoi. hieu van nam thuc day doanh ((thuc va) OR (thuc dan)) te~".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ty hang xa hoi. hieu van nam thuc day doanh ((thuc va) OR (thuc dan)) te*.