diff --git a/src/AbstractDateTime.php b/src/AbstractDateTime.php
index 0b617ff..2fc3515 100644
--- a/src/AbstractDateTime.php
+++ b/src/AbstractDateTime.php
@@ -34,8 +34,6 @@ public function __toString(): string
     }
 
     /**
-     * @param \DateTimeInterface $dateTime
-     *
      * @return static
      */
     public static function createFromDateTime(\DateTimeInterface $dateTime): self
@@ -50,8 +48,6 @@ public static function createFromDateTime(\DateTimeInterface $dateTime): self
     }
 
     /**
-     * @param int $timestamp
-     *
      * @return static
      */
     public static function createFromTimestamp(int $timestamp): self
@@ -62,13 +58,12 @@ public static function createFromTimestamp(int $timestamp): self
     }
 
     /**
-     * @param string        $format
-     * @param string        $dateTime
-     * @param \DateTimeZone $timezone
+     * @param string $format
+     * @param string $dateTime
      *
      * @return static
      */
-    public static function createFromFormat($format, $dateTime, $timezone = null): self
+    public static function createFromFormat($format, $dateTime, \DateTimeZone $timezone = null): self
     {
         $class = static::getClass();
 
@@ -139,21 +134,33 @@ public function getWeekday(): int
         return (int) $this->format('w');
     }
 
+    /**
+     * @return static
+     */
     public function addYears(int $years): DateTimeInterface
     {
         return $this->modify($years.' years');
     }
 
+    /**
+     * @return static
+     */
     public function addMonths(int $months): DateTimeInterface
     {
         return $this->modify($months.' months');
     }
 
+    /**
+     * @return static
+     */
     public function addWeeks(int $weeks): DateTimeInterface
     {
         return $this->modify($weeks.' weeks');
     }
 
+    /**
+     * @return static
+     */
     public function addDays(int $days): DateTimeInterface
     {
         return $this->modify($days.' days');
diff --git a/src/DateTimeInterface.php b/src/DateTimeInterface.php
index d4ac778..5bb2e23 100644
--- a/src/DateTimeInterface.php
+++ b/src/DateTimeInterface.php
@@ -15,80 +15,40 @@
 
 interface DateTimeInterface extends \DateTimeInterface
 {
-    /**
-     * @return string
-     */
     public function __toString(): string;
 
-    /**
-     * @return string
-     */
     public function formatIso(): string;
 
-    /**
-     * @param string $format
-     *
-     * @return string
-     */
     public function formatLocalized(string $format): string;
 
-    /**
-     * @param int $format
-     * @param int $timeFormat
-     *
-     * @return string
-     */
     public function formatIntl(int $format = null, int $timeFormat = null): string;
 
-    /**
-     * @return \DateTime
-     */
     public function toMutable(): \DateTime;
 
-    /**
-     * @return int
-     */
     public function getYear(): int;
 
-    /**
-     * @return int
-     */
     public function getMonth(): int;
 
-    /**
-     * @return int
-     */
     public function getDay(): int;
 
-    /**
-     * @return int
-     */
     public function getWeekday(): int;
 
     /**
-     * @param int $years
-     *
      * @return static
      */
     public function addYears(int $years): self;
 
     /**
-     * @param int $months
-     *
      * @return static
      */
     public function addMonths(int $months): self;
 
     /**
-     * @param int $weeks
-     *
      * @return static
      */
     public function addWeeks(int $weeks): self;
 
     /**
-     * @param int $days
-     *
      * @return static
      */
     public function addDays(int $days): self;
@@ -171,7 +131,10 @@ public function setDate($year, $month, $day);
     public function setISODate($year, $week, $day = 1);
 
     /**
-     * @param \DateInterval $interval
+     * @param int $hour
+     * @param int $minute
+     * @param int $second
+     * @param int $microseconds
      *
      * @return static
      */
diff --git a/src/Holidays/HolidaysInterface.php b/src/Holidays/HolidaysInterface.php
index 12e27d0..68737cd 100644
--- a/src/Holidays/HolidaysInterface.php
+++ b/src/Holidays/HolidaysInterface.php
@@ -16,23 +16,11 @@
 
 interface HolidaysInterface
 {
-    /**
-     * @param DateTimeInterface $dateTime
-     *
-     * @return bool
-     */
     public function isHoliday(DateTimeInterface $dateTime): bool;
 
-    /**
-     * @param DateTimeInterface $dateTime
-     *
-     * @return bool
-     */
     public function isWorkday(DateTimeInterface $dateTime): bool;
 
     /**
-     * @param int|string $year
-     *
      * @return Date[]
      */
     public function getHolidays(int $year): array;
diff --git a/src/Range/AbstractDateTimeRange.php b/src/Range/AbstractDateTimeRange.php
index 7baa8de..6998adf 100644
--- a/src/Range/AbstractDateTimeRange.php
+++ b/src/Range/AbstractDateTimeRange.php
@@ -43,7 +43,7 @@ public function diff(): \DateInterval
         return $this->start->diff($this->end);
     }
 
-    public function diffWorkdays(HolidaysInterface $holidays = null): int
+    public function diffWorkdays(?HolidaysInterface $holidays = null): int
     {
         return $this->start->diffWorkdays($this->end, $holidays);
     }
diff --git a/src/Range/DateTimeRangeInterface.php b/src/Range/DateTimeRangeInterface.php
index a1915e7..ce1cc5d 100644
--- a/src/Range/DateTimeRangeInterface.php
+++ b/src/Range/DateTimeRangeInterface.php
@@ -16,62 +16,25 @@
 
 interface DateTimeRangeInterface
 {
-    /**
-     * @return DateTimeInterface
-     */
     public function getStart(): DateTimeInterface;
 
-    /**
-     * @return DateTimeInterface
-     */
     public function getEnd(): DateTimeInterface;
 
-    /**
-     * @return \DateInterval
-     */
     public function diff(): \DateInterval;
 
-    /**
-     * @param null|HolidaysInterface $holidays
-     *
-     * @return int
-     */
-    public function diffWorkdays(HolidaysInterface $holidays = null): int;
+    public function diffWorkdays(?HolidaysInterface $holidays = null): int;
 
-    /**
-     * @return bool
-     */
     public function isSameYear(): bool;
 
-    /**
-     * @return bool
-     */
     public function isSameMonth(): bool;
 
-    /**
-     * @return bool
-     */
     public function isSameDay(): bool;
 
-    /**
-     * @return bool
-     */
     public function isWholeYear(): bool;
 
-    /**
-     * @return bool
-     */
     public function isWholeMonth(): bool;
 
-    /**
-     * @return bool
-     */
     public function isWholeDay(): bool;
 
-    /**
-     * @param DateTimeInterface $dateTime
-     *
-     * @return bool
-     */
     public function contains(DateTimeInterface $dateTime): bool;
 }