Which common prime minister did Graham Richardson and Bon McMullan serve ?
SELECT DISTINCT ?uri WHERE { <http://dbpedia.org/resource/Graham_Richardson> <http://dbpedia.org/ontology/primeMinister> ?uri. <http://dbpedia.org/resource/Bob_McMullan> <http://dbpedia.org/ontology/primeMinister> ?uri . }
Graham_Richardson Bob_McMullan