add attributions to the README

README.md

@@ -51,9 +51,10 @@ This repository contains the following case studies:
           - Proof of refinement for a pair of fine-grained/coarse-grained
             concurrent stack implementations
 * [spanning-tree](theories/spanning_tree): Proof of a concurrent spanning tree
-  algorithm.
+  algorithm by Amin Timany.
 * [concurrent-stacks](theories/concurrent_stacks): Proof of an implementation of
-  concurrent stacks with helping, as described in the [report](http://iris-project.org/pdfs/2017-case-study-concurrent-stacks-with-helping.pdf).
+  concurrent stacks with helping by Daniel Gratzer et. al., as described in the
+  [report](http://iris-project.org/pdfs/2017-case-study-concurrent-stacks-with-helping.pdf).
 * [lecture-notes](theories/lecture_notes): Coq examples for the
   [Iris lecture notes](http://iris-project.org/tutorial-material.html).