Original: Fabbri was a long time and prolific contributor to the anarchist press in Europe and later South America, including co-editing, along with Errico Malatesta, the paper L'Agitazione.
Simplified: Fabbri was a long time supporter of  to the anarchist press in Europe and later South America, including co-editing, with Errico Malatesta, the paper L'Agitazione.