question: Which German person influenced and was influenced by M1 and M2
query: SELECT DISTINCT ?x0 WHERE {
  ?x0 a ns:people.person .
  ?x0 ns:influence.influence_node.influenced M1 .
  ?x0 ns:influence.influence_node.influenced M2 .
  ?x0 ns:influence.influence_node.influenced_by M1 .
  ?x0 ns:influence.influence_node.influenced_by M2 .
  ?x0 ns:people.person.nationality ns:m.0345h
  }