@article{ELMA_1973__28_141089,
     author = {A. Rotkiewict},
     title = {On {Pyramidal} {Numbers} of {Order} 4.},
     journal = {Elemente der Mathematik},
     pages = {14--16},
     publisher = {mathdoc},
     volume = {28},
     year = {1973},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1973__28_141089/}
}