“…Using the Nehari manifold method along the lines of Szulkin-Weth [20] and Lin-Tang [8] (semilinear problems driven by the Dirichlet Laplacian), we show that for all λ < λ 1 (q) problem (P λ ) has at least three nontrivial solutions, all with sign information (positive, negative and nodal (sign-changing)) and with least energy (ground state solutions). Other existence and multiplicity results for different types of double phase equations, can be found in the papers of Colasuonno-Squassina [2], Gasiński-Papageorgiou [3], Gasiński-Winkert [4][5][6], Liu-Dai [9], Papageorgiou-Rȃdulescu-Repovš [11,12], Papageorgiou-Repovš-Vetro [14], Papageorgiou-Vetro-Vetro [15,16], Rȃdulescu [18], Zeng-Bai-Gasiński-Winkert [22,23].…”