|   [1] Adams R A. Sobolev Spaces. New York:Academic Press, 1975 
[2] Bahri A, Lions P L. Solutions of superlinear elliptic equations and their Morse indices. Comm Pure Appl Math, 1992, 45:1205-1215 
[3] Barrios B, Colorado E, de Pablo A, Sánchez U. On some critical problems for the fractinal Laplacian operator. J Differ Equ, 2012, 252:6133-6162 
[4] Cao D M. Multiple positive solutions of inhomogeneous semilinear elliptic equations unbounded damain in R2. Acta Math Sci, 1994, 14(2):297-312 
[5] Costa D G. Multiplicity results for a class of superlinear elliptic problems. Amer Math Soc, 1993, 48:137-151 
[6] Cabré X, Tan J. Positive solutions of nonlinear problems involving the square root of the Laplacian. Adv Math, 2010, 224:2052-2093 
[7] Caffarelli L, Roquejoffre J M, Sire Y. Variational problems for free boundaries for the fractional Laplacian. J Eur Math Soc, 2010, 12:1151-1179 
[8] Caffarelli L, Salsa S, Silvestre L. Regularity estimates for the fractional Laplacian. Invent Math, 2008, 171:425-461 
[9] Caffarelli L, Silvestre L. An extension problem related to the fractional Laplacian. Commun Part Differ Equ, 2007, 32:1245-1260 
[10] Deng Y B, Li Y, Zhao X J. Multiple solutions for an inhomogeneous semilinear elliptic equation in Rn. Acta Math Sci, 2003, 23(1):1-15 
[11] Ekeland I, Choussoub N. Selected new aspects of the calculus of variations in the large. Bull Amer Math Soc, 2002, 39:207-265 
[12] Li S J, Wang Z Q. Ljusternik-Sohnirelman theorey in partially order Hilber space. Trans Amer Math Soc, 2002, 354:3207-3227 
[13] Liu Z L, Wang Z-Q. Sign-changing solutions of nonlinear elliptic equations. Front Math China, 2008, 3:1-18 
[14] Rabinowitz P H. Some minimax theorems and applications to nonlinear PDE//Nonlinear Analysis. Acad Press, 1978:161-177 
[15] Tan J. Positive solutions for non local elliptic problems. Disc Cont Dyn Syst, 2013, 33:837-859 
[16] Wang Z-Q. On a superlinear elliptic equation. Anal Nonl, 1991, 8:43-58 
[17] Wang Z-Q. Multiplicity results for a class of superlinear elliptic problems. Amer Math Soc, 2004, 133:787-794  |