Update README.md

Author: Penny How

README.md

@@ -23,7 +23,7 @@ How et al. (In Review) Calving controlled by melt-undercutting: detailed mechani
 How (2018) Dynamical change at tidewater glaciers examined using time-lapse photogrammetry. PhD thesis, University of Edinburgh, UK.<br>
 
 <b>*MSc thesis by Lynne Buie, where PyTrx was created in its earliest form*</b><br>
-Addison (2015) PyTrx: feature tracking software for automated production of glacier velocity. MSc thesis, University of Edinburgh, UK. <a href="https://hdl.handle.net/1842/11794">https://hdl.handle.net/1842/11794</a><br>
+Addison (2015) PyTrx: feature tracking software for automated production of glacier velocity. MSc thesis, University of Edinburgh, UK, <a href="https://hdl.handle.net/1842/11794">https://hdl.handle.net/1842/11794</a><br>
 
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