Adding material

Book.lean

@@ -7,6 +7,7 @@ import Book.Quotients
 import Book.Ideals
 import Book.Polynomials
 import Book.Degrees
+import Book.Elements
 import Book.LittleFermat
 import Book.Cauchy
 import Book.Frobenius
@@ -72,6 +73,8 @@ oder der ausführlichen Anleitung am Anfang der
 
 {include 0 Book.Degrees}
 
+{include 0 Book.Elements}
+
 {include 0 Book.LittleFermat}
 
 {include 0 Book.Cauchy}