diff --git a/.travis.yml b/.travis.yml
index 5912d667..ebe47839 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,11 +2,17 @@ language: python
 python:
   - "3.7"
 
-before_script:
-  - "export DISPLAY=:99.0"
-  - "sh -e /etc/init.d/xvfb start"
-  - sleep 3 # give xvfb some time to start
-  
+services:
+  - xvfb
+
+#before_script:
+#  - "export DISPLAY=:99.0"
+#  - "sh -e /etc/init.d/xvfb start"
+#  - sleep 3 # give xvfb some time to start
+
+git:
+  submodules: false
+
 addons:
   apt:
     packages:
diff --git a/README.md b/README.md
index d06ea274..7e9f3844 100644
--- a/README.md
+++ b/README.md
@@ -33,22 +33,18 @@ With DEVSimPy you can:
 
 # Installation
 
-DEVSimPy depends on PyPubSub version 3.3.0 or 3.3.1 and yaml modules: 
+To get DEVSimPy V4.0 package with all Git submodule: 
 ```sh
-$ pip install PyPubSub==3.3.1 pyyaml ruamel.yaml
+$ git clone --recurse-submodules -b version-4.0 --depth=1 https://github.com/capocchi/DEVSimPy.git .
+$ git fetch --unshallow 
 ```
 
+DEVSimPy depends on PyPubSub version 3.3.0 (or 3.3.1), pyyaml, ruamel.yaml and modules. 
 All dependencies can be installed using requirements.txt file:
 ```sh
 $ pip install -r requirements.txt
 ```
 
-To get DEVSimPy V4.0 package with all Git submodule: 
-```sh
-$ git clone --recurse-submodules -b version-4.0 --depth=1 https://github.com/capocchi/DEVSimPy.git .
-$ git fetch --unshallow 
-```
-
 DEVSimPy don't require installation and works on all platforms (). To execute DEVSimPy:
 ```sh
 $ python devsimpy.py
diff --git a/requirements.txt b/requirements.txt
index 3f50fe1c..72576180 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,58 @@
 # Requirements automatically generated by pigar.
 # https://github.com/damnever/pigar
 
+# AttributeEditor.py: 27
+# CheckerGUI.py: 35
+# Components.py: 35,40,42
+# ConnectDialog.py: 23
+# Container.py: 28,29,30,35,37,41
+# ControlNotebook.py: 23,172,174
+# DSV.py: 129,130
+# Decorators.py: 16,18,21
+# DetachedFrame.py: 25
+# DiagramConstantsDialog.py: 4
+# DiagramNotebook.py: 23,30,220,222
+# DirTreeCtrl.py: 32
+# DragList.py: 9
+# DropTarget.py: 16
+# Editor.py: 26,42
+# Event.py: 3
+# ExperimentGenerator.py: 4
+# FTPGUI.py: 4
+# FindGUI.py: 6
+# HtmlWindow.py: 5,6
+# ImportLibrary.py: 34,35
+# LabelGUI.py: 25,26
+# LibPanel.py: 23
+# LibraryTree.py: 23
+# Menu.py: 23
+# Mixins\Savable.py: 263,267
+# Mixins\Selectable.py: 15,73
+# PlotGUI.py: 23,48
+# PluginsGUI.py: 18
+# PreferencesGUI.py: 3,14
+# PrintOut.py: 6
+# PriorityGUI.py: 3
+# PropPanel.py: 23
+# PropertiesGridCtrl.py: 29,30,31,32,33
+# Reporter.py: 4
+# RubberBande.py: 8
+# SimpleFrameEditor.py: 4,5,10
+# SimulationGUI.py: 23,31,33
+# SpreadSheet.py: 25,26,30,32
+# Utilities.py: 38
+# WizardGUI.py: 3,6,13,25
+# XMLModule.py: 19,588
+# YAMLExportGUI.py: 23
+# ZipManager.py: 214
+# devsimpy.py: 81,83,90,99,101,111
+# plugins\blink.py: 13
+# plugins\state_trajectory.py: 20
+# plugins\verbose.py: 14
+# searchTreeList.py: 1
+# wxPyMail.py: 22
+wxPython >= 4.0.6
+
 # Components.py: 44
 # Container.py: 39
 # DiagramNotebook.py: 33
@@ -79,7 +131,7 @@ matplotlib >= 3.1.1
 # PlotGUI.py: 35
 # Utilities.py: 49
 # test_plotly.py: 5
-numpy == 1.17.2
+numpy >= 1.17.2
 
 # DEVSKernel\PyPDEVS\pypdevs221\src\templates\tracer.py: 1
 #package-generator >= 0.0.1
@@ -185,57 +237,5 @@ whichpy >= 0.1
 # PreferencesGUI.py: 6
 #whratio >= 3.1.1
 
-# AttributeEditor.py: 27
-# CheckerGUI.py: 35
-# Components.py: 35,40,42
-# ConnectDialog.py: 23
-# Container.py: 28,29,30,35,37,41
-# ControlNotebook.py: 23,172,174
-# DSV.py: 129,130
-# Decorators.py: 16,18,21
-# DetachedFrame.py: 25
-# DiagramConstantsDialog.py: 4
-# DiagramNotebook.py: 23,30,220,222
-# DirTreeCtrl.py: 32
-# DragList.py: 9
-# DropTarget.py: 16
-# Editor.py: 26,42
-# Event.py: 3
-# ExperimentGenerator.py: 4
-# FTPGUI.py: 4
-# FindGUI.py: 6
-# HtmlWindow.py: 5,6
-# ImportLibrary.py: 34,35
-# LabelGUI.py: 25,26
-# LibPanel.py: 23
-# LibraryTree.py: 23
-# Menu.py: 23
-# Mixins\Savable.py: 263,267
-# Mixins\Selectable.py: 15,73
-# PlotGUI.py: 23,48
-# PluginsGUI.py: 18
-# PreferencesGUI.py: 3,14
-# PrintOut.py: 6
-# PriorityGUI.py: 3
-# PropPanel.py: 23
-# PropertiesGridCtrl.py: 29,30,31,32,33
-# Reporter.py: 4
-# RubberBande.py: 8
-# SimpleFrameEditor.py: 4,5,10
-# SimulationGUI.py: 23,31,33
-# SpreadSheet.py: 25,26,30,32
-# Utilities.py: 38
-# WizardGUI.py: 3,6,13,25
-# XMLModule.py: 19,588
-# YAMLExportGUI.py: 23
-# ZipManager.py: 214
-# devsimpy.py: 81,83,90,99,101,111
-# plugins\blink.py: 13
-# plugins\state_trajectory.py: 20
-# plugins\verbose.py: 14
-# searchTreeList.py: 1
-# wxPyMail.py: 22
-wxPython >= 4.0.6
-
 # DEVSKernel\PyPDEVS\pypdevs221\src\templates\tracer.py: 1
 #yang0textutils >= 0.0.1