The Esperantic Studies Foundation is dedicated to exploring the question of international communication, taking its inspiration from the modest but real success of Esperanto as a language of international and intercultural communication.
Concretely this foundation publishs revues and funds doctoral dissertations about Esperanto and Interlinguistic.
Esperanto Studies: An Overview is an interesting document about all the published research on esperanto.
We can see that there is not so much research about this subject. Few works have been done in sociology, an none in political science.
Despite this, I have noted down some interesting books :
Blanke, Detlev. 1986. Socipolitikaj aspektoj de la Esperanto-movado. Budapest: Hungara Esperanto-Asocio.
Colic, Senad (ed.). 1988. Sociaj aspektoj de la Esperanto-movado. Sarajevo: ELBiH.
Forster, Peter G. 1982. The Esperanto Movement. The Hague: Mouton.
Rasic, Nikola. 1995. La Rondo Familia. Sociologiaj esploroj en Esperantio. Pisa: Edistudio.