diff --git a/thesis.bib b/thesis.bib
index 1de8ffb..487eac5 100644
--- a/thesis.bib
+++ b/thesis.bib
@@ -1003,4 +1003,16 @@
   pages     = {174--185},
   publisher = {{ACM}},
   year      = {1998}
+}
+
+# Unix
+@article{RitchieT74,
+  author    = {Dennis Ritchie and
+               Ken Thompson},
+  title     = {The {UNIX} Time-Sharing System},
+  journal   = {Commun. {ACM}},
+  volume    = {17},
+  number    = {7},
+  pages     = {365--375},
+  year      = {1974}
 }
\ No newline at end of file