G.  D'Angelo, Nibali, V. C., Wanderlingh, U., Branca, C., De Francesco, A., Sacchetti, F., Petrillo, C., and Paciaroni, A., ?Multiple Interacting Collective Modes and Phonon Gap in Phospholipid Membranes?, Journal of Physical Chemistry Letters, vol. 9, pp. 4367-4372, 2018.