diff --git a/alib2algo/src/equations/RegularEquationSolver.h b/alib2algo/src/equations/RegularEquationSolver.h
index 11d067699c60546d50c15288a5ca01ae4cdda0d5..a3d3fb48801692c353f7199866f4cd5cab978390 100644
--- a/alib2algo/src/equations/RegularEquationSolver.h
+++ b/alib2algo/src/equations/RegularEquationSolver.h
@@ -9,6 +9,7 @@
 #define REGULAREQUATIONSOLVER_H_
 
 #include <regexp/unbounded/UnboundedRegExp.h>
+#include <regexp/unbounded/UnboundedRegExpElement.h>
 #include <alphabet/Symbol.h>
 
 #include <map>
diff --git a/alib2algo/src/regexp/convert/ToAutomatonThompson.h b/alib2algo/src/regexp/convert/ToAutomatonThompson.h
index 931a81734a9ae4d942194b481d52a200e95e7d01..e84832bccf09660e5d36d1904fe6f15a560ba865 100644
--- a/alib2algo/src/regexp/convert/ToAutomatonThompson.h
+++ b/alib2algo/src/regexp/convert/ToAutomatonThompson.h
@@ -12,7 +12,9 @@
 
 #include <regexp/RegExp.h>
 #include <regexp/formal/FormalRegExp.h>
+#include <regexp/formal/FormalRegExpElement.h>
 #include <regexp/unbounded/UnboundedRegExp.h>
+#include <regexp/unbounded/UnboundedRegExpElement.h>
 #include <automaton/FSM/EpsilonNFA.h>
 
 namespace regexp {
diff --git a/alib2algo/src/regexp/properties/RegExpEmpty.h b/alib2algo/src/regexp/properties/RegExpEmpty.h
index 8406ca5e9121e444024fa2c257a2ea22bd144b08..598f7e5d178bec69f3b7750600c9b59b1aa1390c 100644
--- a/alib2algo/src/regexp/properties/RegExpEmpty.h
+++ b/alib2algo/src/regexp/properties/RegExpEmpty.h
@@ -12,7 +12,9 @@
 
 #include <regexp/RegExp.h>
 #include <regexp/formal/FormalRegExp.h>
+#include <regexp/formal/FormalRegExpElement.h>
 #include <regexp/unbounded/UnboundedRegExp.h>
+#include <regexp/unbounded/UnboundedRegExpElement.h>
 
 namespace regexp {
 
diff --git a/alib2algo/src/regexp/properties/RegExpEpsilon.h b/alib2algo/src/regexp/properties/RegExpEpsilon.h
index 7fbcd6f0c458736674224a5dc5de1849f816ec5c..ac9ba2968c706a2552f70132695b742d98a6e1ac 100644
--- a/alib2algo/src/regexp/properties/RegExpEpsilon.h
+++ b/alib2algo/src/regexp/properties/RegExpEpsilon.h
@@ -12,7 +12,9 @@
 
 #include <regexp/RegExp.h>
 #include <regexp/formal/FormalRegExp.h>
+#include <regexp/formal/FormalRegExpElement.h>
 #include <regexp/unbounded/UnboundedRegExp.h>
+#include <regexp/unbounded/UnboundedRegExpElement.h>
 
 namespace regexp {
 
diff --git a/alib2algo/src/regexp/transform/RegExpDerivation.h b/alib2algo/src/regexp/transform/RegExpDerivation.h
index 9cf1fc7f1400855bebdf4fce10da03eb3f0a9894..ad6b98361b96058e93dc4d5dac790c29c42db1e2 100644
--- a/alib2algo/src/regexp/transform/RegExpDerivation.h
+++ b/alib2algo/src/regexp/transform/RegExpDerivation.h
@@ -12,7 +12,9 @@
 
 #include <regexp/RegExp.h>
 #include <regexp/formal/FormalRegExp.h>
+#include <regexp/formal/FormalRegExpElement.h>
 #include <regexp/unbounded/UnboundedRegExp.h>
+#include <regexp/unbounded/UnboundedRegExpElement.h>
 
 #include <string/LinearString.h>
 
diff --git a/alib2algo/src/regexp/transform/RegExpIntegral.h b/alib2algo/src/regexp/transform/RegExpIntegral.h
index 122bec3c48e460d4b0edc207422c3888b5b754c5..4dc79e6330f100e4b62608b6a3456112386de04e 100644
--- a/alib2algo/src/regexp/transform/RegExpIntegral.h
+++ b/alib2algo/src/regexp/transform/RegExpIntegral.h
@@ -12,7 +12,9 @@
 
 #include <regexp/RegExp.h>
 #include <regexp/formal/FormalRegExp.h>
+#include <regexp/formal/FormalRegExpElement.h>
 #include <regexp/unbounded/UnboundedRegExp.h>
+#include <regexp/unbounded/UnboundedRegExpElement.h>
 
 #include <string/LinearString.h>
 
diff --git a/alib2data/src/regexp/formal/FormalRegExp.cpp b/alib2data/src/regexp/formal/FormalRegExp.cpp
index a92f4ef00cc90735cc8fe603e87d637c2b42a27c..6acb58b5a4352bd6198242902fb570f3b0c0f21c 100644
--- a/alib2data/src/regexp/formal/FormalRegExp.cpp
+++ b/alib2data/src/regexp/formal/FormalRegExp.cpp
@@ -8,7 +8,6 @@
 #include "FormalRegExp.h"
 #include <exception/AlibException.h>
 #include "FormalRegExpEmpty.h"
-#include "FormalRegExpSymbol.h"
 
 #include <iostream>
 #include <algorithm>
diff --git a/alib2data/src/regexp/formal/FormalRegExp.h b/alib2data/src/regexp/formal/FormalRegExp.h
index 27fb4f07b7033ffc58a7f0de22cbc0ac2d898cb4..ecbb8de2a52e0ce5d5481c508a450c9824570faf 100644
--- a/alib2data/src/regexp/formal/FormalRegExp.h
+++ b/alib2data/src/regexp/formal/FormalRegExp.h
@@ -8,12 +8,10 @@
 #ifndef FORMAL_REG_EXP_H_
 #define FORMAL_REG_EXP_H_
 
-#include <vector>
-#include <list>
 #include <string>
 #include <set>
-#include "FormalRegExpElement.h"
 #include "../RegExpBase.h"
+#include "../../alphabet/Symbol.h"
 #include "../../alphabet/Alphabet.hpp"
 
 namespace regexp {
diff --git a/alib2data/src/regexp/unbounded/UnboundedRegExp.cpp b/alib2data/src/regexp/unbounded/UnboundedRegExp.cpp
index 61054def9e824a06b30a0bfea87a0f13572527a8..65887d82bcec68d72d07391c9b85515000b6035e 100644
--- a/alib2data/src/regexp/unbounded/UnboundedRegExp.cpp
+++ b/alib2data/src/regexp/unbounded/UnboundedRegExp.cpp
@@ -8,7 +8,6 @@
 #include "UnboundedRegExp.h"
 #include <exception/AlibException.h>
 #include "UnboundedRegExpEmpty.h"
-#include "UnboundedRegExpSymbol.h"
 
 #include <iostream>
 #include <algorithm>
diff --git a/alib2data/src/regexp/unbounded/UnboundedRegExp.h b/alib2data/src/regexp/unbounded/UnboundedRegExp.h
index 52db41b45c760e779a718ce432f36974de73e560..2de760735af559c3947a8db42adb4c0ccf64a418 100644
--- a/alib2data/src/regexp/unbounded/UnboundedRegExp.h
+++ b/alib2data/src/regexp/unbounded/UnboundedRegExp.h
@@ -8,12 +8,10 @@
 #ifndef UNBOUNDED_REG_EXP_H_
 #define UNBOUNDED_REG_EXP_H_
 
-#include <vector>
-#include <list>
 #include <string>
 #include <set>
-#include "UnboundedRegExpElement.h"
 #include "../RegExpBase.h"
+#include "../../alphabet/Symbol.h"
 #include "../../alphabet/Alphabet.hpp"
 
 namespace regexp {
diff --git a/astat2/src/RegExpStat.cpp b/astat2/src/RegExpStat.cpp
index bb6803bb0040d20d1f04b7af95d0f9c97741383c..35d32cb164032880341bde63c8426d224e8618ab 100644
--- a/astat2/src/RegExpStat.cpp
+++ b/astat2/src/RegExpStat.cpp
@@ -10,7 +10,9 @@
 #include <exception/AlibException.h>
 
 #include <regexp/formal/FormalRegExp.h>
+#include <regexp/formal/FormalRegExpElement.h>
 #include <regexp/unbounded/UnboundedRegExp.h>
+#include <regexp/unbounded/UnboundedRegExpElement.h>
 
 #include <factory/XmlDataFactory.hpp>
 #include <iostream>