Who is the artist of Sings Kristofferson and also performed Milk Cow Blues atleast once?
SELECT DISTINCT ?uri WHERE { <http://dbpedia.org/resource/Sings_Kristofferson> <http://dbpedia.org/property/artist> ?uri. <http://dbpedia.org/resource/Milk_Cow_Blues> <http://dbpedia.org/ontology/artist> ?uri . }
Sings_Kristofferson Milk_Cow_Blues