Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
cua viet » ca viet, hoa viet, cua vat
may thoi » gay thoi, may thi, tay thoi
dan hanh » dang hanh, dan khanh, dan thanh
thuc dan » thuc hanh, hoc dan, thuc vat
ky mang » ky nang, ke mang, ky dang
may hoi » tay hoi, mai hoi, may hmi
hanh va » hang va, hanh vi
hieu va » hieu qua
va cua » va chua, via cua, ca cua
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky mang ((may hoi) OR (may thoi)). ((hieu va) or (lieu va)) tham thuc dan hanh va cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky mang ((may hoi) OR (may thoi)). ((hieu va) OR (lieu va)) tham thuc dan hanh va cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky mang ((may hoi) OR (may thoi)). ((hieu va) or (lieu va)) tham thuc dan hanh va cua viet".
• Adding a wildcard symbol may retrieve word variants: tu sac ky mang ((may hoi) OR (may thoi)). ((hieu va) or (lieu va)) tham thuc dan hanh va cua viet*.