Ask HN: Resources for understanding of the Tensorflow code?

After reading the Tensorflow white-paper (http://download.tensorflow.org/paper/whitepaper2015.pdf), I realized that I lack understanding of the many topics discussed in the paper. Examples of this include Cross-Device and Multi-Device Communication, Graph Partitioning, Partial Executions and Device Constraints and Optimization (most of section 5 subsections). I want to invest in resources, like courses/books or projects, that help me understand these concepts better. My background is in numerical methods and optimization. I am comfortable with topics discussed in an undergraduate algorithm course. I also can read/write Python/C for numerical calculations.