Kreyssig, Gerhard (1958) Revision du Traite instituant la Communaute Europeenne du Charbon et de l'Acier = Revision of the Treaty establishing the European Coal and Steel Community. [EU European Parliament Document]
van Naters, van der Goes (1955) Le développement de l'intégration économique de l'Europe. Première section: Analyse des documents = The development of the economic integration of Europe. First section: analysis of documents. July 1955. [EU European Parliament Document]
Wigny, Pierre (1959) Una testimonianza sulla Comunita dei Sei = A testimonial on the Community of the Six. [EU European Parliament Document]
Wigny, Pierre. (1957) Un temoignage sur la Communaute des Six = A testimonial on the Community of Six. [EU European Parliament Document]