Uncertainty In Artificial Intelligence 4, edited by R.D. Shachter, T.S. Levitt, L.N. Kanal and J.F. Lemmer (Machine Intelligence and Pattern Recognition Series, vol 9), North-Holland, Amsterdam, 1990, xii + 422 pp. (Hardback $92.25; paperback $48.70)Uncertainty In Artificial Intelligence 5, edited by M. Henrion, R.D. Shachter, L.N. Kanal and J.F. Lemmer (Machine Intelligence and Pattern Recognition Series, vol 10), North-Holland, Amsterdam, 1990, xiv + 459 pp. (Hardback $92.25; paperback $48.75).