Hi Hardings,
Unfortunately, I do not have an electronic copy of the paper. I will keep my eyes open for a scanner. If I find one, I'll scan the paper then email it to you. If you have access to achival files, here are the key references:
G. W. Wester and R. D. Middlebrook, Low Frequency Characterization of Switched Dc-to-Dc Converters, Proc. IEEE Power Electronics Specialists Conference, 1972 Record.
R. D. Middlebrook and S. M. Cuk, A General Unified Approach to Modelling Switching Converter Power Stages, Proc. IEEE Power Electronics Specialists Conference, 1976 Record.
S. M. Cuk and R. D. Middlebrook, A General Unified Approach to Modelling Switching Dc-to-Dc Converters in Discontinuous Conduction Mode, Proc. IEEE Power Electronics Specialists Conference, 1977 Record.
Drs. Middlebrook and Cuk had a consulting company called TESLAco. It may still be there. I found a website for TESLAco. They may still sell their books, which are collections of papers, including the ones I listed.
http://www.teslaco.com/teslaco.htmlAlso, the second order model I referred to was not for the inductor, it was for the average switch/diode behavior. If you tell me the basic topology you are using, buck, boost, buck/boost (i.e. step down, step up, step up/down), I can slap together some mathematics to clarify my statements.
-Jess