In the past A.F. Vakakis has collaborated on articles with D.S. Sophianopoulos and M.A.F. Aziz. One of their most recent publications is Forced localization in a periodic chain of non-linear oscillators. Which was published in journal International Journal of Non-Linear Mechanics.
More information about A.F. Vakakis research including statistics on their citations can be found on their Copernicus Academic profile page.