He collaborated with singers such as Peter Schreier, Aldo Baldin, Ria Bollen, Ursula Buckel, Eva Csapó, Agnes Giebel, Julia Hamari, Ernst Haefliger, Philippe Huttenlocher, Georg Jelden, Helena Jungwirth, Siegfried Lorenz, Adalbert Kraus, Horst Laubenthal, Karl Markus, Barbara Martig-Tüller, Friedreich Melzer, Klaus Mertens, Siegmund Nimsgern, Ernst-Gerold Schramm, Verena Schweizer, Jakob Stämpfli, Ortrun Wenkel, Kurt Widmer and Edith Wiens.
Julia Roberts | Julia Kristeva | Julia Child | Julia Smith | Julia Ward Howe | Julia Fischer | Julia Sweeney | Julia Ormond | Julia Stiles | Julia Fordham | Julia Copus | Julia | Raúl Juliá | Raul Julia | Julia Foster | Julia Donaldson | Julia Smit | Julia Phillips | Julia Morley | Julia Morgan | Julia McKenzie | Julia Margaret Cameron | Julia Lathrop | Julia de Burgos | Julia Davis | Julia Cho | Julia Bradbury | Sant Julia de Loria | Julia Zemiro | Julia Strachey |