- TODO
- http://www.ra.cs.uni-tuebingen.de/lehre/ss12/advanced_ml/lecture3.pdf
- http://www.wikiwand.com/en/Mercer%27s_condition
- http://www.wikiwand.com/en/Reproducing_kernel_Hilbert_space
- http://www.wikiwand.com/en/Hilbert_space
- http://www.gatsby.ucl.ac.uk/~gretton/coursefiles/lecture4_introToRKHS.pdf
- http://www.kernel-machines.org/publications/pdfs/0701907.pdf
- http://www.ics.uci.edu/~welling/classnotes/papers_class/Kernel-Ridge.pdf