Perhaps you should try some spelling variations:
thac thuc » thach thuc, thuc thuc, thac thuy
hieu van » hieu va, thien van, lieu va
van thac » van hac, van tham, van than
so sach » so sanh, bo sach, co sach
nang ma » tang ma, sang ma, nang cao
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
danh di » danh du, xanh di, danh dien
cuu tre » cua tre, cau tren, cau treo
di cuu » di cau, di cua, dinh cuu

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach y ((nang x) or (nang ma)) hoi. hieu van thac thuc va danh di cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y ((nang x) OR (nang ma)) hoi. hieu van thac thuc va danh di cuu tre*.