a classification system for the antigens of human blood; used in blood transfusion therapy; four groups are A and B and AB and O

a classification system for the antigens of human blood; used in blood transfusion therapy; four groups are A and B and AB and O

a classification system for the antigens of human blood; used in blood transfusion therapy; four groups are A and B and AB and O

a classification system for the antigens of human blood; used in blood transfusion therapy; four groups are A and B and AB and O

a classification system for the antigens of human blood; used in blood transfusion therapy; four groups are A and B and AB and O