src/HOL/Analysis/Linear_Algebra.thy

   then show "h = g" by (simp add: ext)
 qed
 
 text \<open>TODO: The following lemmas about adjoints should hold for any
   Hilbert space (i.e. complete inner product space).
-  (see \<^url>\<open>http://en.wikipedia.org/wiki/Hermitian_adjoint\<close>)
+  (see \<^url>\<open>https://en.wikipedia.org/wiki/Hermitian_adjoint\<close>)
 \<close>
 
 lemma adjoint_works:
   fixes f :: "'n::euclidean_space \<Rightarrow> 'm::euclidean_space"
   assumes lf: "linear f"