M. Kojima and S. Shindo, " Extensions of Newton and quasi-Newton methods to systems of PC 1 equations," Journal of Operations Research Society of Japan, 29 (1986), pp. 352–374. 14.
Nigel Clarke ;Kevin Parrott, Multigrid for American option pricing with stochastic volatility. Volume
6, Issue
3 September 1999 , pages 177 - 195