T. Singh and Mukti Acharya, Skolem graceful signed graphs, Extended abstract published in Electronic Notes in Discrete Mathematics, Vol. 15 (2003), 9-10.
T. Singh and Mukti Acharya, Graceful signed graphs: V. Union of k copies of the cycle of length three with one vertex in common, International Journal of Management & Systems (IJOMAS), Vol. 20(3), (2004), 246-254