Olivier Maillet, Xin Zhou,Rasul R. Gazizulin, Bojan R. Ilic, Jeevak M. Parpia, Olivier Bourgeois, Andrew D. Fefferman, and Eddy CollinACS Nano, 2018, 12 (6), pp 5753–5760 DOI: 10.1021/acsnano.8b01634 ACS Nano "Measuring Frequency Fluctuations in Nonlinear Nanomechanical Resonators"