Nonlinear laser spectroscopy by Atkins, C, Hancock, G, Zacharias, H, Beverini, N, Galli, M, Inguscio, M, Strumia, F, Bionducci, G, Bloomfield, L, Gerhardt, H, Hänsch, T, Boulnois, J, Aubourg, P, Van Lerberghe, A, Agrawal, G, Boyd, R, Harter, D, Chen, H, Erbert, G, Garrett, W, Payne, MG, Ferrell, W, Miller, J, Compton, R, Greenland, P