Sober Approach Spaces are Firmly Reflective for the Class of Epimorphic Embeddings. - A. Gerlo; Eva Vandersmissen; C. Van Olmen (Appl. Categorical Struct., 2006)

Approach Theory in a Category: A Study of Compactness and Hausdorff Separation. - A. Gerlo (Appl. Categorical Struct., 2008)