diff --git a/app/Http/helpers.php b/app/Http/helpers.php
index 8d8cf10..87cf47b 100644
--- a/app/Http/helpers.php
+++ b/app/Http/helpers.php
@@ -1,6 +1,6 @@
 <?php
 
-/*
+/**
  * Returns true with a given percentage.
  *
  * @param  int     $prob Probability for true in percent.
@@ -20,7 +20,7 @@ function rand_bool($prob = 50) {
     return $rand <= $prob;
 }
 
-/*
+/**
  * Return the formatted string representation of a floatng point number.
  *
  * The decimal point is a ',', the thousands seperator ist set to '.'.
@@ -34,3 +34,29 @@ function rand_bool($prob = 50) {
 function formatAmount(float $amount, $decimals = 2) {
     return number_format($amount, $decimals, ',', '.');
 }
+
+/**
+ * Return the string that is the first day of the month, given by the year and
+ * the month.
+ *
+ * @param string $year
+ * @param string $month
+ * @return string 
+ */
+function startOfMonth($year, $month) {
+    return Carbon\Carbon::createFromDate($year, $month)
+                        ->startOfMonth()->format('Y-m-d');
+}
+
+/**
+ * Return the string that is the last day of the month, given by the year and
+ * the month.
+ *
+ * @param string $year
+ * @param string $month
+ * @return string 
+ */
+function endOfMonth($year, $month) {
+    return Carbon\Carbon::createFromDate($year, $month)
+                        ->endOfMonth()->format('Y-m-d');
+}
diff --git a/resources/views/bookings/index.blade.php b/resources/views/bookings/index.blade.php
index 1c2f4d2..39a05a2 100644
--- a/resources/views/bookings/index.blade.php
+++ b/resources/views/bookings/index.blade.php
@@ -29,7 +29,7 @@
             <tr style='color: red; font-weight: bold'>
                 <td></td>
                 <td></td>
-                <td>{{ $year . '-' . sprintf('%02d', $month) . '-01'}}</td>
+                <td>{{ startOfMonth($year, $month) }}</td>
                 <td>Saldo</td>
                 <td></td>
                 <td></td>
@@ -71,7 +71,7 @@
                     </td>
                 </tr>
                 @if (!$booking->isSimple())
-                    @foreach ($booking->subBookings() as $subBooking)
+                    @foreach ($booking->subBookings as $subBooking)
                         <tr>
                             <td>+</td>
                             <td></td>
@@ -80,12 +80,12 @@
                             <td></td>
                             <td align='right'>
                                 @if ($subBooking->signedAmount() < 0)
-                                    {{ formatAmount($subBooking->signedAmount) }}
+                                    {{ formatAmount($subBooking->signedAmount()) }}
                                 @endif
                             </td>
                             <td align='right'>
                                 @if ($subBooking->signedAmount() >= 0)
-                                    {{ formatAmount($subBooking->signedAmount) }}
+                                    {{ formatAmount($subBooking->signedAmount()) }}
                                 @endif
                             </td>
                             <td>
@@ -103,8 +103,7 @@
                 <td></td>
                 <td></td>
                 <td>
-                    {{ $year . '-' . sprintf('%02d', $month) . '-' .
-                       cal_days_in_month(CAL_GREGORIAN, $month, $year) }}
+                    {{ endOfMonth($year, $month) }}
                 </td>
                 <td>Monatsabschluss</td>
                 <td></td>
@@ -117,8 +116,7 @@
                 <td></td>
                 <td></td>
                 <td>
-                    {{ $year . '-' . sprintf('%02d', $month) . '-' .
-                       cal_days_in_month(CAL_GREGORIAN, $month, $year) }}
+                    {{ endOfMonth($year, $month) }}
                 </td>
                 <td>Saldo</td>
                 <td></td>