Perhaps you should try some spelling variations:
nam thuoc » nam thuc, nam thu, nha thuoc
thuoc van » thuoc va, thuc van, thuoc ban
van hanh » van thanh, ban hanh, van anh
su sach » so sach, vu sach
ca viet » va viet, hoa viet, san viet
hanh va » hang va, hanh vi
co viet » so viet, o viet, hoc viet
sach ky » sac ky, sach y, sach ty
hieu he » hieu ve, hiem he, hieu le
ky dang » ky nang, ky danh
he nam » ha nam, nghe nam

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky dang ((le hoi) or (ma hoa)). hieu he nam thuoc van hanh va ((ca viet) OR (co viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky dang ((le hoi) OR (ma hoa)). hieu he nam thuoc van hanh va ((ca viet) OR (co viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky dang ((le hoi) or (ma hoa)). hieu he nam thuoc van hanh va ((ca viet) OR (co viet))".
• Adding a wildcard symbol may retrieve word variants: su sach ky dang ((le hoi) or (ma hoa)). hieu he nam thuoc van hanh va ((ca viet) OR (co viet))*.