Project(OrderBy(Filter((?src != ?src2),
                       BGP( ?term <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2000/01/rdf-schema#Class> .
                            ?term <http://purl.org/dc/terms/source> ?src .
                            ?term <http://www.w3.org/2000/01/rdf-schema#label> ?term_label .
                            ?term <http://www.w3.org/2000/01/rdf-schema#subClassOf> ?term2 .
                            ?term2 <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2000/01/rdf-schema#Class> .
                            ?term2 <http://purl.org/dc/terms/source> ?src2 .
                            ?term2 <http://www.w3.org/2000/01/rdf-schema#label> ?term_label2)), (?src)),
        {?term_label, ?src, ?term_label2, ?src2})