2758 20160701171710.0 ASTROimport-915 Lobel, A. 2013 Long-term Spectroscopic Monitoring of Cool Hypergiants HR 8752, IRC+10420, and 6 Cas near the Yellow Evolutionary Void We discuss the spectral variability of three white (A-type) hypergiants (Ia+) near the region of atmospheric dynamical instability in the upper H-R diagram, called the Yellow Evolutionary Void. The Void represents an obstacle for the fast blueward evolution of the most massive cool hypergiant stars. Optical and near-IR spectra observed between 1993 and 2011 with several high-resolution spectrographs, including the WHT-Utrecht Echelle Spectrograph, Mercator-HERMES, NOT-Sofin, and Keck-HIRES, are compared to investigate the wind-physics and -dynamics of the hypergiants. de Jager, K. Nieuwenhuijzen, H. 370 Years of Astronomy in Utrecht 470 2013 167 http://esoads.eso.org/abs/2013ASPC..470..167L published in NONREF