Volker Krause, J. David Singer "Minor Powers, Alliances, And Armed Conflict: Some Preliminary Patterns", in "Small States and Alliances", 2001, pp 15–23, ISBN978-3-7908-2492-6 (Print) ISBN978-3-662-13000-1 (Online) [1]
Fulvio Attinà "State aggregation in defense pacts: systemic explanations", Jean Monnet Working Papers, University of Catania, nr. 56, November 2004, ISSN 2281-9029 [2]