Perhaps you should try some spelling variations:
tham thuc » pham thuc, tam thuc, thai thuc
nham thuc » nhan thuc, nham thu, pham thuc
nang mai » nang ma, nang tai, lang mai
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
mai hoi » mai khoi, dai hoi, lai hoi
va hanh » van hanh, va thanh, va danh
cuu tre » cua tre, cau tren, cau treo
tu cai » tu cac, tu can, tu bai
cai ky » cao ky, cac ky, cam ky
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 cai ky nang mai hoi. hieu van ((tham thuc) or (((nham thuc) or (nam thuc)))) va hanh vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu cai ky nang mai hoi. hieu van ((tham thuc) OR (((nham thuc) OR (nam thuc)))) va hanh vi cuu tre.
• Adding a wildcard symbol may retrieve word variants: tu cai ky nang mai hoi. hieu van ((tham thuc) or (((nham thuc) or (nam thuc)))) va hanh vi cuu tre*.