http://ismir2012.ismir.net/event/papers/295_ISMIR_2012.pdf

http://ismir2012.ismir.net/event/papers/LBD2.pdf

(There's usually a few "doesn't work" comments, but imagine how much extra processing is required to get the fundamental when you run guitars thru delay/ reverb, overdrive/distortion, chorus/tremolo/vibrato etc effects)