Update README.md

Author: dervinism

README.md

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 # kdeModalityTest
 Matlab kernel density excess mass estimate of data modality described by Fisher and Marron (2001).
 
-Reference:  N. I. Fisher and J. S. Marron, "Mode Testing via the Excess Mass Estimate," Biometrika 88 (2), 499-517 (2001).
+References: N. I. Fisher and J. S. Marron, "Mode Testing via the Excess Mass Estimate," Biometrika 88 (2), 499-517 (2001).
+            G. S. Watson, “Goodness-of-Fit Tests on a Circle. I,” Biometrika 48 (1–2), 109–114 (1961).
+            D. Muir, "Kernel density estimation for circular functions"
+            (https://www.mathworks.com/matlabcentral/fileexchange/44072-kernel-density-estimation-for-circular-functions),
+            MATLAB Central File Exchange. Retrieved June 7, 2020.