diff --git a/citations.bib b/citations.bib
index e373451..7271750 100644
--- a/citations.bib
+++ b/citations.bib
@@ -27,3 +27,17 @@
   url    = {https://www.thrustcurve.org/},
   author = {Coker, John}
 }
+
+
+@book{cengel_thermodynamics,
+  address    = {New York},
+  edition    = {Eighth edition},
+  title      = {Thermodynamics: an engineering approach},
+  isbn       = {9780073398174},
+  shorttitle = {Thermodynamics},
+  publisher  = {McGraw-Hill Education},
+  author     = {Çengel, Yunus A. and Boles, Michael A.},
+  year       = {2015},
+  note       = {OCLC: ocn869741544},
+  keywords   = {Thermodynamics}
+}