diff --git a/command-line.c b/command-line.c
index c610df9..ceb90f6 100644
--- a/command-line.c
+++ b/command-line.c
@@ -17,6 +17,17 @@
  * along with GDSII-Converter.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+/**
+ * @file command-line.c
+ * @brief Function to render according to command line parameters
+ * @author Mario Hüttel <mario.huettel@gmx.net>
+ */
+
+/**
+ * @addtogroup MainApplication
+ * @{
+ */
+
 #include <stdio.h>
 #include "command-line.h"
 #include "gds-parser/gds-parser.h"
@@ -24,6 +35,12 @@
 #include "cairo-output/cairo-output.h"
 #include "latex-output/latex-output.h"
 
+/**
+ * @brief Delete layer_info and free nem element.
+ *
+ * Like delete_layer_info_struct() but also frees layer_info::name
+ * @param info
+ */
 static void delete_layer_info_with_name(struct layer_info *info)
 {
 	if (info) {
@@ -33,6 +50,19 @@ static void delete_layer_info_with_name(struct layer_info *info)
 	}
 }
 
+/**
+ * @brief Convert GDS according to supplied parameters
+ * @param gds_name GDS File path
+ * @param pdf_name Cairo-PDF path
+ * @param tex_name TeX/TikZ path
+ * @param pdf Render Cairo
+ * @param tex Render LaTeX
+ * @param layer_file Layer mapping file
+ * @param cell_name Cell name to render
+ * @param scale Scale image down by this value
+ * @param pdf_layers TikZ creates OCG layers
+ * @param pdf_standalone LaTeX document is standalone
+ */
 void command_line_convert_gds(char *gds_name, char *pdf_name, char *tex_name, gboolean pdf, gboolean tex,
 			      char *layer_file, char *cell_name, double scale, gboolean pdf_layers, gboolean pdf_standalone)
 {
@@ -135,3 +165,5 @@ destroy_file:
 
 
 }
+
+/** @} */
diff --git a/command-line.h b/command-line.h
index 143460e..eaa9de8 100644
--- a/command-line.h
+++ b/command-line.h
@@ -17,6 +17,17 @@
  * along with GDSII-Converter.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+/**
+ * @file command-line.c
+ * @brief Render according to command line parameters
+ * @author Mario Hüttel <mario.huettel@gmx.net>
+ */
+
+/**
+ * @addtogroup MainApplication
+ * @{
+ */
+
 #ifndef _COMMAND_LINE_H_
 #define _COMMAND_LINE_H_
 #include <glib.h>
@@ -25,3 +36,5 @@ void command_line_convert_gds(char *gds_name, char *pdf_name, char *tex_name, gb
 			      char *layer_file, char *cell_name, double scale, gboolean pdf_layers, gboolean pdf_standalone);
 
 #endif /* _COMMAND_LINE_H_ */
+
+/** @} */
diff --git a/layer-selector.c b/layer-selector.c
index 08e929c..6eb9e1a 100644
--- a/layer-selector.c
+++ b/layer-selector.c
@@ -17,6 +17,17 @@
  * along with GDSII-Converter.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+/**
+ * @file layer-selection.c
+ * @brief Implementation of the layer selector
+ * @author Mario Hüttel <mario.huettel@gmx.net>
+ */
+
+/**
+ * @addtogroup MainApplication
+ * @{
+ */
+
 #include "layer-selector.h"
 #include "gds-parser/gds-parser.h"
 #include "widgets/layer-element.h"
@@ -89,6 +100,11 @@ void clear_list_box_widgets(GtkListBox *box)
 	gtk_widget_set_sensitive(global_save_button, FALSE);
 }
 
+/**
+ * @brief Check if specific layer number is present in list box
+ * @param layer Layer nu,ber
+ * @return TRUE if present
+ */
 static gboolean check_if_layer_widget_exists(int layer) {
 	GList *list;
 	GList *temp;
@@ -110,6 +126,11 @@ static gboolean check_if_layer_widget_exists(int layer) {
 	return ret;
 }
 
+/**
+ * @brief Analyze \p cell and append used layers to list box
+ * @param listbox listbox to add layer
+ * @param cell Cell to analyze
+ */
 static void analyze_cell_layers(GtkListBox *listbox, struct gds_cell *cell)
 {
 	GList *graphics;
@@ -129,7 +150,15 @@ static void analyze_cell_layers(GtkListBox *listbox, struct gds_cell *cell)
 	}
 }
 
-gint sort_func(GtkListBoxRow *row1, GtkListBoxRow *row2, gpointer unused)
+/**
+ * @brief sort_func Sort callback for list box
+ * @param row1
+ * @param row2
+ * @param unused
+ * @note Do not use this function
+ * @return
+ */
+static gint sort_func(GtkListBoxRow *row1, GtkListBoxRow *row2, gpointer unused)
 {
 	LayerElement *le1, *le2;
 	gint ret;
@@ -170,6 +199,12 @@ void generate_layer_widgets(GtkListBox *listbox, GList *libs)
 	gtk_widget_set_sensitive(global_save_button, TRUE);
 }
 
+/**
+ * @brief Find LayerElement in list with specified layer number
+ * @param el_list List with elements of type LayerElement
+ * @param layer Layer number
+ * @return Found LayerElement. If nothing is found, NULL.
+ */
 static LayerElement *find_layer_element_in_list(GList *el_list, int layer)
 {
 	LayerElement *ret = NULL;
@@ -182,6 +217,10 @@ static LayerElement *find_layer_element_in_list(GList *el_list, int layer)
 	return ret;
 }
 
+/**
+ * @brief Load file and apply layer definitions to listbox
+ * @param file_name CSV Layer Mapping File
+ */
 static void load_layer_mapping_from_file(gchar *file_name)
 {
 	GFile *file;
@@ -252,6 +291,11 @@ destroy_file:
 	g_object_unref(file);
 }
 
+/**
+ * @brief Callback for Load Mapping Button
+ * @param button
+ * @param user_data
+ */
 static void load_mapping_clicked(GtkWidget *button, gpointer user_data)
 {
 	GtkWidget *dialog;
@@ -269,6 +313,12 @@ static void load_mapping_clicked(GtkWidget *button, gpointer user_data)
 	gtk_widget_destroy(dialog);
 }
 
+/**
+ * @brief Create Line for LayerMapping file with supplied information
+ * @param layer_element information
+ * @param line_buffer buffer to write to
+ * @param max_len Maximum length that cna be used in \p line_buffer
+ */
 static void create_csv_line(LayerElement *layer_element, char *line_buffer, size_t max_len)
 {
 	GString *string;
@@ -304,6 +354,11 @@ static void create_csv_line(LayerElement *layer_element, char *line_buffer, size
 	g_string_free(string, TRUE);
 }
 
+/**
+ * @brief Save layer mapping of whole list box into file
+ * @param file_name layer mapping file
+ * @param list_box listbox
+ */
 static void save_layer_mapping_data(const gchar *file_name, GtkListBox *list_box)
 {
 	FILE *file;
@@ -331,6 +386,11 @@ static void save_layer_mapping_data(const gchar *file_name, GtkListBox *list_box
 	fclose(file);
 }
 
+/**
+ * @brief Callback for Save Layer Mapping Button
+ * @param button
+ * @param user_data
+ */
 static void save_mapping_clicked(GtkWidget *button, gpointer user_data)
 {
 	GtkWidget *dialog;
@@ -361,3 +421,5 @@ void setup_save_mapping_callback(GtkWidget *button,  GtkWindow *main_window)
 	global_save_button = button;
 	g_signal_connect(button, "clicked", G_CALLBACK(save_mapping_clicked), main_window);
 }
+
+/** @} */
diff --git a/layer-selector.h b/layer-selector.h
index 2338d18..0fd7c18 100644
--- a/layer-selector.h
+++ b/layer-selector.h
@@ -17,6 +17,12 @@
  * along with GDSII-Converter.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+/**
+ * @file layer-selector.h
+ * @brief Implementation of the Layer selection list
+ * @author Mario Hüttel <mario.huettel@gmx.net>
+ */
+
 #ifndef __LAYER_SELECTOR_H__
 #define __LAYER_SELECTOR_H__
 
@@ -24,10 +30,38 @@
 #include <glib.h>
 #include "mapping-parser.h"
 
+/**
+ * @brief Generate layer widgets in \p listbox
+ * @note This clears all previously inserted elements
+ * @param listbox
+ * @param libs The library to add
+ */
 void generate_layer_widgets(GtkListBox *listbox, GList *libs);
-void setup_load_mapping_callback(GtkWidget *button, GtkWindow *main_window);
-void setup_save_mapping_callback(GtkWidget *button, GtkWindow *main_window);
-GList *export_rendered_layer_info();
-void delete_layer_info_struct(struct layer_info *info);
 
+/**
+ * @brief Supply button for loading the layer mapping
+ * @param button
+ * @param main_window Parent window for dialogs
+ */
+void setup_load_mapping_callback(GtkWidget *button, GtkWindow *main_window);
+
+/**
+ * @brief Supply button for saving the layer mapping
+ * @param button
+ * @param main_window
+ */
+void setup_save_mapping_callback(GtkWidget *button, GtkWindow *main_window);
+
+/**
+ * @brief get the layer information present in the listbox of the selector
+ * @return List with layer_info elements
+ */
+GList *export_rendered_layer_info();
+
+/**
+ * @brief Delete a layer_info struct
+ * @param info Struct to be deleted.
+ * @note The layer_info::name Element has to be freed manually
+ */
+void delete_layer_info_struct(struct layer_info *info);
 #endif /* __LAYER_SELECTOR_H__ */
diff --git a/main-window.c b/main-window.c
index f700628..fabc19f 100644
--- a/main-window.c
+++ b/main-window.c
@@ -17,6 +17,16 @@
  * along with GDSII-Converter.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+/**
+ * @file main-window.c
+ * @brief Handling of GUI
+ * @author Mario Hüttel <mario.huettel@gmx.net>
+ */
+
+/** @addtogroup MainApplication
+ * @{
+ */
+
 #include "main-window.h"
 #include <stdio.h>
 #include "gds-parser/gds-parser.h"
@@ -27,6 +37,9 @@
 #include "widgets/conv-settings-dialog.h"
 #include "cairo-output/cairo-output.h"
 
+/**
+ * @brief User data supplied to callback function of the open button
+ */
 struct open_button_data {
 	GtkWindow *main_window;
 	GList **list_ptr;
@@ -34,17 +47,33 @@ struct open_button_data {
 	GtkListBox *layer_box;
 };
 
+/**
+ * @brief User data supplied to callback function of the convert button
+ */
 struct convert_button_data {
 	GtkTreeView *tree_view;
 	GtkWindow *main_window;
 };
 
+/**
+ * @brief Window close event of main window
+ *
+ * Closes the main window. This leads to the termination of the whole application
+ * @param window main window
+ * @param user not used
+ * @return TRUE. This indicates that the event has been fully handled
+ */
 static gboolean on_window_close(gpointer window, gpointer user)
 {
 	gtk_widget_destroy(GTK_WIDGET(window));
 	return TRUE;
 }
 
+/**
+ * @brief generate string from gds_time_field
+ * @param date Date to convert
+ * @return String with date
+ */
 static GString *generate_string_from_date(struct gds_time_field *date)
 {
 	GString *str;
@@ -59,7 +88,11 @@ static GString *generate_string_from_date(struct gds_time_field *date)
 	return str;
 }
 
-
+/**
+ * @brief Callback function of Load GDS button
+ * @param button
+ * @param user Necessary Data
+ */
 static void on_load_gds(gpointer button, gpointer user)
 {
 	GList *cell;
@@ -161,6 +194,11 @@ end_destroy:
 	gtk_widget_destroy(open_dialog);
 }
 
+/**
+ * @brief Convert button callback
+ * @param button
+ * @param user
+ */
 static void on_convert_clicked(gpointer button, gpointer user)
 {
 	static struct render_settings sett = {
@@ -247,8 +285,15 @@ ret_layer_destroy:
 	g_list_free_full(layer_list, (GDestroyNotify)delete_layer_info_struct);
 }
 
-/* This function activates/deactivates the convert button depending on whether
- * a cell is selected for conversion or not */
+
+/**
+ * @brief Callback for cell-selection change event
+ *
+ * This function activates/deactivates the convert button depending on whether
+ * a cell is selected for conversion or not
+ * @param sel
+ * @param convert_button
+ */
 static void cell_selection_changed(GtkTreeSelection *sel, GtkWidget *convert_button)
 {
 	GtkTreeModel *model = NULL;
@@ -314,3 +359,5 @@ GtkWindow *create_main_window()
 
 	return (conv_data.main_window);
 }
+
+/** @} */
diff --git a/main-window.h b/main-window.h
index ec9a0a3..6799ec0 100644
--- a/main-window.h
+++ b/main-window.h
@@ -17,11 +17,30 @@
  * along with GDSII-Converter.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+/**
+ * @file main-window.h
+ * @brief Header for main-window
+ * @author Mario Hüttel <mario.huettel@gmx.net>
+ */
+
 #ifndef _MAIN_WINDOW_H_
 #define _MAIN_WINDOW_H_
 
+/**
+ * @addtogroup MainApplication
+ * @{
+ */
+
 #include <gtk/gtk.h>
 
+/**
+ * @brief Create main window
+ *
+ * This function creates the main window and sets the necessary callback routines.
+ * @return
+ */
 GtkWindow *create_main_window();
 
+/** @} */
+
 #endif /* _MAIN_WINDOW_H_ */