Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
thanh tai » thanh hai, thanh toan, doanh tai
va thanh » gia thanh, ban thanh, va tinh
dang xay » dang van, van xay
cuu tre » cau tren, cau treo
cua tre » cua te, cua triet, dua tren
thuc va » thuc vat, thuc dan, thuc day
va tham » van tham, va cham, va thuat
hieu va » lieu va, hieu qua
lang xa » lang ha, lang van
sai ky » sac ky
te sai » te tai, te bai, te lai

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sai ky ((lang xa) OR (dang xay)) hoi. hieu va tham thuc va thanh tai ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sai ky ((lang xa) OR (dang xay)) hoi. hieu va tham thuc va thanh tai ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sai ky ((lang xa) OR (dang xay)) hoi. hieu va tham thuc va thanh tai ((cua tre) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: te sai ky ((lang xa) OR (dang xay)) hoi. hieu va tham thuc va thanh tai ((cua tre) or (cuu tre))*.