added rocket textbook

citations.bib

@@ -41,3 +41,14 @@
   note       = {OCLC: ocn869741544},
   keywords   = {Thermodynamics}
 }
+
+@book{sutton_rocket_2001,
+  address   = {New York},
+  edition   = {7th ed},
+  title     = {Rocket propulsion elements},
+  isbn      = {9780471326427},
+  publisher = {John Wiley \& Sons},
+  author    = {Sutton, George P. and Biblarz, Oscar},
+  year      = {2001},
+  keywords  = {Rocket engines}
+}