I first heard of J. Focken’s dissertation (De Gregorii Nazianzeni Orationum et Carminum Dogmaticorum Argumentandi Ratione) reading through Frederick W. Norris’ introduction to his commentary on Gregory of Nazianzus’ Five Theological Orations (Faith Gives Fullness to Reasoning: The Five Theological Orations of Gregory Nazianzen, Leiden: Brill, 1991). He (Norris) seemed to rely heavily on Focken’s analysis, and so I thought it worth looking for. Finding the bibliography, I noticed that it was published in 1912, and so wondered if it was now public domain. I was having very little success until I stumbled upon a microfilm version of it on Archive.org: http://archive.org/details/degregoriinazian00fock! What’s even better is that it’s written in Latin (as all good dissertations once were), so it would be a great way for me to practice. 
Enjoy!
Juicy! Thanks! (Says this current Ancient Phil. master’s Aristotelian—er student.)
Good to know that someone else gets excited about these sorts of things as I do.