@article{KJM_2018_42_3_a4,
     author = {J. Reunsumrit and T. Sitthiwirattham},
     title = {A {New} {Class} of {Four-Point} {Fractional} {Sum} {Boundary} {Value} {Problems} for {Nonlinear} {Sequential} {Fractional} {Difference} {Equations} {Involving} {Shift} {Operators}},
     journal = {Kragujevac Journal of Mathematics},
     pages = {371 },
     publisher = {mathdoc},
     volume = {42},
     number = {3},
     year = {2018},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/KJM_2018_42_3_a4/}
}