Winkelmann seems to have come to anarcho-syndicalism by way of the International Transport Workers Federation, at the time administered by General Secretary Edo Fimmen a left socialist , industrial internationalist and advocate of using union power to counter-attack against fascism


If someone has the time and skills to translate, this would be a great addition to libcom library.
Winkelmann played an important role in exposing German nazis working underground in Spain.
http://www.plusloin.org/gimenez/article.php3?id_article=353