[1] Alves C O, Ambrosio V, Isernia T.Existence, multiplicity and concentration for a class of fractional $p\&q$-Laplacian problems in $\mathbb{R}^{n}$. Commun Pure Appl Anal, 2019, 18(4): 2009-2045
[2] Ambrosio V.A Kirchhoff type equation in $\mathbb{R}^{n}$ involving the fractional ($p$,$q$)-Laplacian. J Geom Anal, 2022, 32(4): 135
[3] Ambrosio V.Multiple solutions for a fractional $p$-Laplacian equation with sign-changing potential. Electron J Differential Equations, 2016, 151: 1-12
[4] Ambrosio V, Figueiredo G, Isernia T.Existence and concentration of positive solutions for $p$-fractional Schrödinger equations. Ann Mat Pura Appl, 2020, 199(1): 317-344
[5] Ambrosio V, Isernia T.A multiplicity result for a ($p$,$q$)-Schrödinger-Kirchhoff type equation. Ann Mat Pura Appl, 2022, 201(2): 943-984
[6] Ambrosio V, Isernia T.Multiplicity and concentration results for some nonlinear Schrödinger equations with the fractional $p$-Laplacian. Discrete Contin Dyn Syst, 2018, 38(11): 5835-5881
[7] Ambrosio V, Isernia T. Multiplicity of positive silutions of a fractional $p\&q$-Laplacian problem in $\mathbb{R}^{n}$. J Math Anal Appl, 2021, 501(1): Art 124487
[8] Ambrosio V, Isernia T.On the multiplicity and concentration for $p$-fractional Schrödinger equations. Appl Math Lett, 2019, 95: 13-22
[9] Ambrosio V, Isernia T, R$\breve{\rm a}$dulescu V. Concentration of positive solutions for a class of fractional $p$-Kirchhoff type equations. Proc Roy Soc Edinburgh Sect A, 2021, 151(2): 601-651
[10] Bartolo R, Candela A M, Salvatore A.On a class of superlinear $p\&q$-Laplacian type equations on $\mathbb{R}^{n}$. J Math Anal Appl, 2016, 438(1): 29-41
[11] Bobkov V, Tanaka M.On sign-changing solutions for $p\&q$-Laplace equations with two parameters. Adv Nonlinear Anal, 2019, 8(1): 101-129
[12] Brasco L, Lindgren E, Schikorra A.Higher Hölder regularity for the fractional $p$-Laplacian in the superquadratic case. Adv Math, 2018, 338: 782-846
[13] Caffarelli L, Gidas B, Spruck J.Asymptotic symmetry and local behavior of semilinear elliptic equations with critical Sobolev growth. Comm Pure Appl Math, 1989, 42: 271-297
[14] Chen C, Bao J.Existence, nonexistence, and multiplicity of solutions for the fractional $p\&q$-Laplacian equation in $\mathbb{R}^{n}$. Bound Value Probl, 2016, 2016: 1-16
[15] Chen W, Li C.Classification of solutions of some nonlinear elliptic equations. Duke Math J, 1991, 63(3): 615-622
[16] Chen W, Li C.Maximum principles for the fractional $p$-Laplacian and symmetry of solutions. Adv Math, 2018, 335: 735-758
[17] Chen W, Li C, Li Y.A direct method of moving planes for fractional laplacian. Adv Math, 2016, 308: 404-437
[18] Chen W, Li C, Li Y.Symmetry of solutions for nonlinear problems involving fully nonlinear nonlocal operators. Calc Var Partial Differential Equations, 2017, 272: 4131-4157
[19] De Filippis C, Palatucci G.Hölder regularity for nonlocal double phase equations. J Differ Equations, 2019, 267(1): 547-586
[20] De Giorgi E.Convergence problems for functionals and operator// Proceedimhs of the International Meeting on Recent Methods in Nonlinear Analysis (Rome, 1978), Pitagora, Bologna, 1979: 131-188
[21] Duan Y, Wei Y.Properties of fractional $p$-Laplace equations with sign-changing potential. Nonlinear Anal, 2024, 249: 113628
[22] Figueiredo G M.Existence of positive solutions for a class of $p\&q$ elliptic problems with critical growth on $\mathbb{R}^{n}$. J Math Anal Appl, 2011, 378: 507-518
[23] Gidas B, Ni W, Nirenberg L.Symmetry and related properties via maximum principle. Comm Math Phys, 1979, 68: 209-243
[24] Gidas B, Ni W, Nirenberg L.Symmetry of positive solutions of nonlinear elliptic equations in $\mathbb{R}^{n}$// Adv Math Suppl Stud, Mathematical Analysis and Applications 7. New York, London: Academic Press, 1981: 369-402
[25] He C, Li G.The existence of a nontrivial solution to the $p\&q$-Laplacian problem with nonlinearity asymptotic to $u^{p-1}$ at infinity in $\mathbb{R}^{n}$. Nonlinear Anal, 2008, 68(5): 1100-1119
[26] He C, Li G.The regularity of weak solutions to nonlinear scalar field elliptic equations containing $p\&q$-Laplacians. Ann Acad Sci Fenn Math, 2008, 33(2): 337-371
[27] Iannizzotto A, Mosconi S, Squassina M.Global Hölder regularity for the fractional $p$-Laplacian. Revista Matemática Iberoamericana, 2016, 32(4): 1353-1392
[28] Isernia T.Fractional $p\&q$-Laplacian problems with potentials vanishing at infinity. Opuscula Math, 2020, 40(1): 93-110
[29] Isernia T, Repov$\breve{\rm s}$ D. Nodal solutions for double phase Kirchhoff problems with vanishing potentials. Asymptot Anal, 2021, 124(3/4): 371-396
[30] Jin L, Li Y.A Hopf's lemma and the boundary regularity for the fractional $p$-Laplacian. Discrete Contin Dyn Syst, 2019, 39(3): 1477-1495
[31] Li G, Guo Z.Multiple solutions for the $p\&q$-Laplacian problem with critical exponent. Acta Math Sci, 2009, 29B(4): 903-918
[32] Li G, Liang X.The existence of nontrivial solutions to nonlinear elliptic equation of $p\&q$-Laplacian type on $\mathbb{R}^{n}$. Nonlinear Anal, 2009, 71: 2316-2334
[33] Li Z, Zhang Q.Sub-solutions and a point-wise Hopf's lemma for fractional $p$-Laplacian. Communications on Pure and Applied Analysis, 2021, 20(2): 835-865
[34] Liu Z, Chen W.Maximum principles and monotonicity of solutions for fractional $p$-equations in unbounded domains. J Differ Equations, 2021, 270: 1043-1078
[35] Mosconi S, Perera K, Squassina M, et al. The Brezis-Nirenberg problem for the fractional $p$-Laplacian. Calc Var Partial Differential Equations, 2016, 55(4): Art 105
[36] Radulescu A D, Xiang M, Zhang B.Existence of solutions for perturbed fractional $p$-Laplacian equations. J Differ Equations, 2016, 260(2): 1392-1413
[37] Serrin J.A symmetry problem in potential theory. Arch Ration Mech Anal, 1971, 43: 304-318
[38] Wu L, Chen W. The sliding methods for the fractional $p$-Laplacian. Adv Math, 2020, 361: Art 106933