An outline of non-abelian cohomology in a topos : (I) The theory of bouquets and gerbes John Duskin — 1982 Cahiers de Topologie et Géométrie Différentielle Catégoriques
Simplicial matrices and the nerves of weak n -categories I: Nerves of bicategories. Duskin, John W. — 2001 Theory and Applications of Categories [electronic only]