Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
dan hanh » dang hanh, dan khanh, dan thanh
thuc dan » thuc hanh, hoc dan, thuc vat
hieu va » hieu qua
ky mang » ky nang, ke mang, ky dang
may hoi » may thoi, tay hoi, may hmi
hanh va » hang va, hanh vi
mai hoi » mai khoi, dai hoi, lai hoi
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky
va hoa » van hoa, va hoc, ma hoa

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