@article{PA_2020_9_2_a1,
     author = {M. A. Almalahi and M. S. Abdo and S. K. Panchal},
     title = {Periodic boundary value problems for fractional implicit differential equations involving {Hilfer} fractional derivative},
     journal = {Problemy analiza},
     pages = {16--44},
     publisher = {mathdoc},
     volume = {9},
     number = {2},
     year = {2020},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PA_2020_9_2_a1/}
}