Nonlinear excitations and bound states of electrons, holes and solitons in bilayers of triangular lattices Alexander P. Chetverikov, Werner Ebeling, Eckehard Schöll and Manuel G. Velarde Eur. Phys. J. B, 92 6 (2019) 122 Published online: 10 June 2019 DOI: 10.1140/epjb/e2019-90715-8