Muhammad Salam and Nasir Rashid and Shah Khalid and Muhammad Raees Khan, A NXM Version of 5X5 Playfair Cipher for any Natural Language (Urdu as Special Case). journal = {International Journal of Computer and Information Engineering}, [online]. World Academy of Science, Engineering and Technology. January 2011, vol. 49(1). 66 - 68 [viewed 19 April 2024]. Available from: https://publications.waset.org/pdf/9796.