The general theory of memristors, meminductors, memcapacitors of any order (first order memristor is the genuine one invented in 1971 by Professor Leon Chua, however he generalized recently his discover to second, third order memristor, etc.)is published in a paper I wrote with him on september 2014 in International Journal of Bifurcation and Chaos. One can download it freely from the site
https://www.researchgate.net/publication/261676241_MEMFRACTA...