diff --git a/src/Motorradvermietung.cpp b/src/Motorradvermietung.cpp
index 82eae40..d37d22b 100644
--- a/src/Motorradvermietung.cpp
+++ b/src/Motorradvermietung.cpp
@@ -69,7 +69,6 @@ auto int_to_string(const unsigned int value, const unsigned int digits = 0) -> s
  */
 class date final
 {
-private:
     unsigned short day_;
     unsigned short month_;
     unsigned short year_;
@@ -123,7 +122,6 @@ public:
  */
 class address final
 {
-private:
     string street_;
     string street_no_;
     string postal_code_;
@@ -158,13 +156,13 @@ public:
         return istr;
     }
 
-	/**
-	 * \brief Output operator of address
-	 * \param ostr output stream
-	 * \param address current address
-	 * \return output stream
-	 */
-	friend ostream& operator<<(ostream& ostr, const address& address)
+    /**
+     * \brief Output operator of address
+     * \param ostr output stream
+     * \param address current address
+     * \return output stream
+     */
+    friend ostream& operator<<(ostream& ostr, const address& address)
     {
         ostr << "Strasse: " << address.street_ << endl;
         ostr << "Hausnummer: " << address.street_no_ << endl;
@@ -174,9 +172,11 @@ public:
     }
 };
 
+/**
+ * \brief Customer, represented by name, first name, address, phone and year of birth
+ */
 class customer final
 {
-private:
     int id_;
     string name_;
     string first_name_;
@@ -200,6 +200,12 @@ public:
     {
     }
 
+    /**
+     * \brief Input operator of customer
+     * \param istr input stream
+     * \param customer current address instance
+     * \return output stream
+     */
     friend istream& operator>>(istream& istr, customer*& customer)
     {
         cout << "Name: ";
@@ -215,6 +221,12 @@ public:
         return istr;
     }
 
+    /**
+     * \brief Output operator of customer
+     * \param ostr output stream
+     * \param customer current customer instance
+     * \return output stream
+     */
     friend ostream& operator<<(ostream& ostr, const customer& customer)
     {
         ostr << "Name: " << customer.name_ << endl;
@@ -226,29 +238,43 @@ public:
         return ostr;
     }
 
+    /**
+     * \brief get name of customer
+     * \return name
+     */
     string get_name() const
     {
         return name_;
     }
 
+    /**
+     * \brief get first name of customer
+     * \return first name
+     */
     string get_first_name() const
     {
         return first_name_;
     }
 
+    /**
+     * \brief get the value, if customer hast driving license
+     * \return True if customer hast driving license. False otherwise.
+     */
     bool get_has_driving_license() const
     {
         return has_driving_license_;
     }
 };
 
+/**
+ * \brief Reservation of a motorcycle
+ */
 class reservation final
 {
-private:
     int id_;
     date start_;
     date end_;
-    short motorcycle_ = -1; // => -1 means nothing reserved
+    short motorcycle_index_ = -1; // => -1 means nothing reserved
     customer* customer_;
     bool canceled_;
 public:
@@ -256,27 +282,43 @@ public:
         id_(++next_reservation_id),
         start_(start),
         end_(end),
-        motorcycle_(motorcycle),
+        motorcycle_index_(motorcycle),
         customer_(customer),
         canceled_(false)
     {
     }
 
+    /**
+     * \brief get start date of reservation
+     * \return date instance
+     */
     date get_start_date() const
     {
         return start_;
     }
 
+    /**
+     * \brief get end date of reservation
+     * \return date instance
+     */
     date get_end_date() const
     {
         return end_;
     }
 
-    short get_motorcycle() const
+    /**
+     * \brief get index of motorcycle array
+     * \return integer value of index
+     */
+    short get_motorcycle_index() const
     {
-        return motorcycle_;
+        return motorcycle_index_;
     }
 
+    /**
+     * \brief get pointer of customer, attached to this instance
+     * \return pointer to customer
+     */
     customer* get_customer() const
     {
         return customer_;
@@ -458,7 +500,7 @@ bool validate_reservation(reservation* const reservation)
     const auto end_sum = reservation->get_end_date().get_day_num();
     for (auto r : reservations)
     {
-        if (r->get_motorcycle() == reservation->get_motorcycle())
+        if (r->get_motorcycle_index() == reservation->get_motorcycle_index())
         {
             if (start_sum < r->get_end_date().get_day_num() && end_sum > r->get_start_date().get_day_num()
                 || end_sum > r->get_start_date().get_day_num() && end_sum < r->get_end_date().get_day_num())
@@ -528,7 +570,7 @@ reservation* get_reservation_for_customer(customer* const current_customer)
         if (reservation->get_customer() == current_customer)
         {
             cout << ++index << ". " << reservation->get_start_date() << " - " << reservation->get_end_date() << ": " <<
-                motorcycles[reservation->get_motorcycle()] << endl;
+                motorcycles[reservation->get_motorcycle_index()] << endl;
             reservations_of_customer.push_back(reservation);
         }
     }
@@ -585,7 +627,7 @@ void export_reservations()
     for (auto reservation : reservations)
     {
         f << reservation->get_id() << ";";
-        f << motorcycles[reservation->get_motorcycle()] << ";";
+        f << motorcycles[reservation->get_motorcycle_index()] << ";";
         f << reservation->get_start_date() << ";";
         f << reservation->get_end_date() << ";";
         f << reservation->get_customer()->get_name() << ";";