Preface
(1970)
Prefazione
(2011)
Vorwort
(1975)
Vorwort der Herausgeber
(2011)
Foreword
(1960)
Editor's Perspective
(1978)
Editor's Perspective
(1978)
Éditorial
(2004)
Preface
(1972)
Vorwort
(1978)