Perhaps you should try some spelling variations:
thuoc sac » thuoc sach, thuoc dac, thuoc sai
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
sac ky » cac ky, sai ky
va dam » van dam, va dao, va dau
dam tu » nam tu, cam tu, tam tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc sac ky ((nang xa) or (lang xa)) hoi. hieu va dam tu va hanh vi ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sac ky ((nang xa) OR (lang xa)) hoi. hieu va dam tu va hanh vi ((cua tre) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: thuoc sac ky ((nang xa) or (lang xa)) hoi. hieu va dam tu va hanh vi ((cua tre) or (cuu tre))*.