by Whitehead, J.T., Chisholm, W.A., Anderson, J.G., Clayton, R., Elahi, H., Eriksson, A.J., Grzybowski, S., Hileman, A.R., Janischewskyj, W., Longo, V.J., Moser, C.H., Mousa, A.M., Orville, R.E., Parrish, D.E., Rizk, F.A.M., Renowden, J.R.
Published in IEEE transactions on power delivery (01.07.1993)

by Orville, Richard E., Pyle, Richard B., Henderson, Ronald W.
Published in IEEE transactions on power systems (01.11.1986)