Appell, Jürgen, Espedito De Pascale and Alfonso Vignoli. Nonlinear Spectral Theory. Berlin, Boston: De Gruyter, 2008. Web. Retrieved 19 Jun. 2013, from http://www.degruyter.com/view/product/178648

Appell, J., De Pascale, E. & Vignoli, A. (2008). Nonlinear Spectral Theory. Berlin, Boston: De Gruyter. Retrieved 19 Jun. 2013, from http://www.degruyter.com/view/product/178648

Appell, Jürgen, Espedito De Pascale and Alfonso Vignoli. 2008. Nonlinear Spectral Theory. Berlin, Boston: De Gruyter. Retrieved 19 Jun. 2013, from http://www.degruyter.com/view/product/178648