diff --git a/dh.h b/dh.h
index fc23e9fb..64cb811b 100644
--- a/dh.h
+++ b/dh.h
@@ -9,6 +9,7 @@
 
 #include "cryptlib.h"
 #include "gfpcrypt.h"
+#include "algebra.h"
 
 NAMESPACE_BEGIN(CryptoPP)
 
diff --git a/ec2n.h b/ec2n.h
index 826b2e43..f89fd7bd 100644
--- a/ec2n.h
+++ b/ec2n.h
@@ -11,6 +11,7 @@
 #include "cryptlib.h"
 #include "gf2n.h"
 #include "integer.h"
+#include "algebra.h"
 #include "eprecomp.h"
 #include "smartptr.h"
 #include "pubkey.h"
diff --git a/ecp.h b/ecp.h
index 6c3b44dc..29d40329 100644
--- a/ecp.h
+++ b/ecp.h
@@ -8,6 +8,7 @@
 
 #include "cryptlib.h"
 #include "integer.h"
+#include "algebra.h"
 #include "modarith.h"
 #include "eprecomp.h"
 #include "smartptr.h"
diff --git a/eprecomp.cpp b/eprecomp.cpp
index ad6ea891..5161290a 100644
--- a/eprecomp.cpp
+++ b/eprecomp.cpp
@@ -6,6 +6,7 @@
 
 #include "eprecomp.h"
 #include "integer.h"
+#include "algebra.h"
 #include "asn.h"
 
 NAMESPACE_BEGIN(CryptoPP)
diff --git a/luc.h b/luc.h
index bfd37597..bd04dee5 100644
--- a/luc.h
+++ b/luc.h
@@ -7,6 +7,7 @@
 #include "cryptlib.h"
 #include "gfpcrypt.h"
 #include "integer.h"
+#include "algebra.h"
 #include "secblock.h"
 
 #if CRYPTOPP_MSC_VERSION
diff --git a/modexppc.h b/modexppc.h
index ebfcf6f0..a1a0a9c7 100644
--- a/modexppc.h
+++ b/modexppc.h
@@ -4,6 +4,7 @@
 #include "cryptlib.h"
 #include "modarith.h"
 #include "integer.h"
+#include "algebra.h"
 #include "eprecomp.h"
 #include "smartptr.h"
 #include "pubkey.h"
diff --git a/mqv.h b/mqv.h
index 5d30de24..aa5ba8f6 100644
--- a/mqv.h
+++ b/mqv.h
@@ -10,6 +10,7 @@
 #include "gfpcrypt.h"
 #include "modarith.h"
 #include "integer.h"
+#include "algebra.h"
 #include "misc.h"
 
 NAMESPACE_BEGIN(CryptoPP)
diff --git a/pubkey.h b/pubkey.h
index 4b6f28a3..8cdabe56 100644
--- a/pubkey.h
+++ b/pubkey.h
@@ -43,6 +43,7 @@
 
 #include "cryptlib.h"
 #include "integer.h"
+#include "algebra.h"
 #include "modarith.h"
 #include "filters.h"
 #include "eprecomp.h"
diff --git a/xtr.cpp b/xtr.cpp
index 459f8ffe..9819b81d 100644
--- a/xtr.cpp
+++ b/xtr.cpp
@@ -5,6 +5,7 @@
 #include "xtr.h"
 #include "nbtheory.h"
 #include "integer.h"
+#include "algebra.h"
 #include "modarith.h"
 #include "algebra.cpp"
 
diff --git a/xtr.h b/xtr.h
index f520cf5e..d38bae95 100644
--- a/xtr.h
+++ b/xtr.h
@@ -1,17 +1,19 @@
 #ifndef CRYPTOPP_XTR_H
 #define CRYPTOPP_XTR_H
 
-/** \file
-	"The XTR public key system" by Arjen K. Lenstra and Eric R. Verheul
-*/
+//! \file xtr.h
+//! \brief The XTR public key system
+//! \details The XTR public key system by Arjen K. Lenstra and Eric R. Verheul
 
 #include "cryptlib.h"
 #include "modarith.h"
 #include "integer.h"
+#include "algebra.h"
 
 NAMESPACE_BEGIN(CryptoPP)
 
-//! an element of GF(p^2)
+//! \class GFP2Element
+//! \brief an element of GF(p^2)
 class GFP2Element
 {
 public:
@@ -40,7 +42,8 @@ public:
 	Integer c1, c2;
 };
 
-//! GF(p^2), optimal normal basis
+//! \class GFP2_ONB
+//! \brief GF(p^2), optimal normal basis
 template <class F>
 class GFP2_ONB : public AbstractRing<GFP2Element>
 {
@@ -208,6 +211,7 @@ protected:
 	mutable Integer t;
 };
 
+//! \brief Creates primes p,q and generator g for XTR
 void XTR_FindPrimesAndGenerator(RandomNumberGenerator &rng, Integer &p, Integer &q, GFP2Element &g, unsigned int pbits, unsigned int qbits);
 
 GFP2Element XTR_Exponentiate(const GFP2Element &b, const Integer &e, const Integer &p);