I have just added the following Friedrich Bleek books to the electronic books listing:
Bleek, Friedrich. Der Brief an die Hebraer erlautert durch Einleitung, Uebersetzung, und fortlaufenden Commentar. Vol. 1. 1828.
Bleek, Friedrich. Der Brief an die Hebraer. Vol. 2 Part 1. 1836.
Bleek, Friedrich. Der Brief an die Hebraer. Vol. 2 Part 2. 1840.
Bleek, Friedrich. Der Hebraerbrief. Edited by Karl August Windrath. 1868.
I don't know how I missed them!
Also I added the following book a few days ago:
Huyghe, P. Carolo. Commentarius in Epistolam ad Hebraeos. 1901.
I am continually adding new resources as I come across them, so if you know of something that is missing, I would appreciate it if you would let me know.