Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
ca viet » co viet, hoa viet, san viet
hanh va » hang va, hanh vi
sach ky » sac ky, sach y, sach ty
vu sach » vu bach, su sach, vu khach
ky dang » ky nang, ky danh
va viet » hoa viet, san viet, mai viet
me hoi » le hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky dang ((me hoi) or (ma hoa)). hieu van nam thuc van hanh va ((ca viet) or (va viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky dang ((me hoi) OR (ma hoa)). hieu van nam thuc van hanh va ((ca viet) OR (va viet)).
• Adding a wildcard symbol may retrieve word variants: vu sach ky dang ((me hoi) or (ma hoa)). hieu van nam thuc van hanh va ((ca viet) or (va viet))*.