Anderson, D.R., Moats, L.M. (2007)

Electronic Journal of Qualitative Theory of Differential Equations [electronic only]

Nagoya, Hajime, Grammaticos, Basil, Ramani, Alfred (2008)

SIGMA. Symmetry, Integrability and Geometry: Methods and Applications [electronic only]

Smith, B. (1986)

International Journal of Mathematics and Mathematical Sciences

Wituła, Roman, Słota, Damian (2007)

Journal of Integer Sequences [electronic only]