One on CMOS implementation:
C.F. Lee and P.K.T. Mok, “A Monolithic Current-Mode CMOS DC-DC Converter with On-Chip Current-Sensing Technique,” IEEE Journal of Solid-State Circuits, Vol. 39, No. 1, pp. 3-14, Jan 2004.
Another one on Loop Model and Gain Analysis:  
W.H. Ki, "Signal flow graph in loop gain analysis of DC-DC PWM CCM switching converters", IEEE Trans. on Ckts. & Sys., Part I, Vol.45, No.6, pp.644-655, June, 1998.