Update README.md

Author: mdbrnowski

README.md

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-# pythagorean-tuples
+# Pythagorean tuples
 A direct method to generate Pythagorean triples, quadruples and n-tuples.
+
+## Source
+This repository is a implementation of a great paper by Tanay Roy and Farjana Jaishmin Sonia from Jadavpur University, India. It is called "A Direct Method To Generate Pythagorean Triples And Its Generalization To Pythagorean Quadruples And n-tuples". I am very thankful to them. 🙏
+
+If you would like to read their paper, it is [here](https://arxiv.org/ftp/arxiv/papers/1201/1201.2145.pdf).