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

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 danh ((me hoi) or (ma hoa)). hieu ve am thuc van hanh va ((ca viet) OR (co viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky danh ((me hoi) OR (ma hoa)). hieu ve am thuc van hanh va ((ca viet) OR (co viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky danh ((me hoi) or (ma hoa)). hieu ve am thuc van hanh va ((ca viet) OR (co viet))".
• Adding a wildcard symbol may retrieve word variants: vu sach ky danh ((me hoi) or (ma hoa)). hieu ve am thuc van hanh va ((ca viet) OR (co viet))*.