1 files changed, 20 insertions, 10 deletions

diff --git a/ref.bib b/ref.bib
index 92ff8f0..8df5c0b 100644
--- a/ref.bib
+++ b/ref.bib
@@ -1,14 +1,24 @@
 @book{maclane,
-  author = {Mac Lane, Saunders},
-  title = {Categories for the Working Mathematician},
-  year = 1971,
-  publisher = {Springer-Verlag New York, Inc.},
-  langid = {english}
+    author = {Mac Lane, Saunders},
+    title = {Categories for the Working Mathematician},
+    year = 1971,
+    publisher = {Springer-Verlag New York, Inc.},
+    langid = {english}
 }
 @book{joyofcats,
-  author = {Adámek, Jiří and Herrlich, Horst and Strecker, George},
-  title = {Abstract and Concrete Categories: The Joy of Cats},
-  year = {1990},
-  publisher = {John Wiley \& Sons, Inc.},
-  langid = {english}
+    author = {Adámek, Jiří and Herrlich, Horst and Strecker, George},
+    title = {Abstract and Concrete Categories: The Joy of Cats},
+    year = {1990},
+    publisher = {John Wiley \& Sons, Inc.},
+    langid = {english}
+}
+@article{one-universe,
+    author = {Mac Lane, Saunders},
+    title = {One universe as a foundation for category theory},
+    year = {1969},
+    journaltitle = {Reports of the Midwest Category Seminar III. Lecture Notes in Mathematics},
+    volume = {106},
+    publisher = {Springer},
+    doi = {10.1007/BFb0059147},
+    langid = {english}
 }
\ No newline at end of file