Perhaps you should try some spelling variations:
tham thuc » nham thuc, tam thuc, thai thuc
pham thuc » phap thuc, pham chuc, nham thuc
nham thu » nham thuc, nam thu, pham thu
hieu van » hieu va, thien van, lieu va
va hanh » van hanh, va thanh, va danh
cuu tre » cua tre, cau tren, cau treo
ky tang » ky nang, ky dang, kho tang
tang ma » mang may, tang van
bai ky » ban ky, sai ky, bac ky
ma hoi » mai hoi, xa hoi, ma hoa
vi cuu » vi luu, vinh cuu
tu bai » tu ban, tu bat, te bai

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu bai ky tang ma hoi. hieu van ((tham thuc) or (((pham thuc) or (nham thu)))) va hanh vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu bai ky tang ma hoi. hieu van ((tham thuc) OR (((pham thuc) OR (nham thu)))) va hanh vi cuu tre.
• Adding a wildcard symbol may retrieve word variants: tu bai ky tang ma hoi. hieu van ((tham thuc) or (((pham thuc) or (nham thu)))) va hanh vi cuu tre*.