There is an excellent paper by Andrei Kreptul (Seattle University School of Law) online entitled, "The Constitutional Right of Secession in Political Theory and History". The paper consists of two parts, one analyzes the political theory underlying the right of secession, and the other places the right of secession within its international historical context of present day constitutions. RECOMMENDED READING!
On a slightly different note, a new book will be published later this year which I am looking forward to, "The Myth of National Defense", and will be edited by Hans-Hermann Hoppe. The subject matter will be war, foreign policy and defense, with about a dozen papers published. It will cover the sacrosanct topic of public goods in national defense in a critical manner. For some interesting discussion on this subject, a revised edition of Gordon Tullock's classic, Exporations in the Theory of Anarchy is online with some valuable additional commentary. See in particular, Jeffrey Rogers Hummel's contributions.
Just a thought.