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

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 thach thuc va danh di ((cuu tre) OR (cua 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 thach thuc va danh di ((cuu tre) OR (cua tre))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach y ((nang x) or (nang ma)) hoi. hieu van thach thuc va danh di ((cuu tre) OR (cua tre))*".