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

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 ve 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 ve nam thuc van hanh va ((ca viet) OR (va viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky dang ((me hoi) or (ma hoa)). hieu ve 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 ve nam thuc van hanh va ((ca viet) OR (va viet))*.