All these links are in French. If you can read this language, then you will see that the polemics go back a very long way.

• Intégrisme (Wikipedia article).
• Les Amis du Christ-Roi en France – containing several documents on historical intégrisme.
• Alain de Benoist, Psychologie du Conspirationnisme (pdf).
• Sodalitium n°60 (décembre 2007) with very well researched articles.
• Page of issues of Sodalitium in pdf. No English downloads available.

As I mentioned in my earlier article, Sodalitium is the review of the Istituto Mater Boni Consilii, a group of priests in Italy who aspire to restoring the status quo of the Church under Pius X. They are much more “extreme” than the Society of St Pius X from which they are dissidents, and hold a position about the Pope (since 1958) close to sedevacantism. Les Amis du Christ-Roi, based at Nantes, are even more extreme.

And a couple of books by one of the greatest scholars in the subject, which give more balance in historical and intellectual terms:

• Emile Poulat, Intégrisme et Catholicisme Intégral, Paris 1969.
• Émile Poulat, Catholicisme, démocratie et socialisme. Le mouvement catholique et Mgr Benigni de la naissance du socialisme à la victoire du fascisme, Paris 1977.