Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
duy sang » duy van, duy can, duy anh
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
thuc va » thuc vat, thuc dan, thuc day
cuu tre » cua tre, cau tren, cau treo
y sang » _ sang
ma hoi » mai hoi, ma hoa, me hoi
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
vi cuu » vi luu, vinh cuu

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ((y sang) or (duy sang)) ((ma hoi) or (xa hoi)). hieu van nam thuc va dan vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((y sang) OR (duy sang)) ((ma hoi) OR (xa hoi)). hieu van nam thuc va dan vi cuu tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ((y sang) or (duy sang)) ((ma hoi) or (xa hoi)). hieu van nam thuc va dan vi cuu tre*.