diff --git a/module/fid/src/Validator/SubitoPartialCopyPageBounds.php b/module/fid/src/Validator/SubitoPartialCopyPageBounds.php
index 35bc8a99f5372974f73ec0dbfafe0cafcd82692f..c3fb3f86f3eef77757b5a89395f2d55ddaa0d7fd 100644
--- a/module/fid/src/Validator/SubitoPartialCopyPageBounds.php
+++ b/module/fid/src/Validator/SubitoPartialCopyPageBounds.php
@@ -1,7 +1,11 @@
 <?php
 /**
+ * Subito partial copy page bounds validator
+ *
  * Copyright (C) 2020 Leipzig University Library
  *
+ * PHP Version 7
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
@@ -15,13 +19,25 @@
  * with this program; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
- * @author  Alexander Purr <purr@ub.uni-leipzig.de>
- * @license http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @category VuFind
+ * @package  Validator
+ * @author   Alexander Purr <purr@ub.uni-leipzig.de>
+ * @license  http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @link     https://vufind.org/wiki/development Wiki
  */
 namespace fid\Validator;
 
 use Zend\Validator\AbstractValidator;
 
+/**
+ * Subito partial copy page bounds validator
+ * 
+ * @category VuFind
+ * @package  Validator
+ * @author   Alexander Purr <purr@ub.uni-leipzig.de>
+ * @license  http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @link     https://vufind.org/wiki/development Wiki
+ */
 class SubitoPartialCopyPageBounds extends AbstractValidator
 {
     use SubitoPartialCopyPageRangeValidatorTrait;
@@ -37,14 +53,23 @@ class SubitoPartialCopyPageBounds extends AbstractValidator
         self::PAGE_BOUNDS => "acquisition_error_page_bounds",
     ];
 
-    public function isValid($value)
+    /**
+     * Validate if given page range is beetween first and last page of a record
+     *
+     * @param string $value From to page range
+     *
+     * @return bool
+     */
+    public function isValid(string $value) : bool
     {
         if ($this->options['numberPages'] == null) {
             return false;
         }
-        $this->extractPages($value);
+        $this->_extractPages($value);
 
-        if (($this->pageEnd > $this->options['numberPages']) || ($this->pageStart < 1)) {
+        if (($this->_pageEnd > $this->options['numberPages'])
+            || ($this->_pageStart < 1)
+        ) {
             $this->error(self::PAGE_BOUNDS);
             return false;
         } else {
diff --git a/module/fid/src/Validator/SubitoPartialCopyPageOrder.php b/module/fid/src/Validator/SubitoPartialCopyPageOrder.php
index 0415c5a348decedb3bc25eb9ce008bc2b1d67d57..891087e3f7c06b33b53c9adf3a4bd3128aee15fe 100644
--- a/module/fid/src/Validator/SubitoPartialCopyPageOrder.php
+++ b/module/fid/src/Validator/SubitoPartialCopyPageOrder.php
@@ -1,7 +1,11 @@
 <?php
 /**
+ * Subito partial copy page order validator
+ *
  * Copyright (C) 2020 Leipzig University Library
  *
+ * PHP Version 7
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
@@ -15,13 +19,25 @@
  * with this program; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
- * @author  Alexander Purr <purr@ub.uni-leipzig.de>
- * @license http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @category VuFind
+ * @package  Validator
+ * @author   Alexander Purr <purr@ub.uni-leipzig.de>
+ * @license  http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @link     https://vufind.org/wiki/development Wiki
  */
 namespace fid\Validator;
 
 use Zend\Validator\AbstractValidator;
 
+/**
+ * Subito partial copy page order validator
+ *
+ * @category VuFind
+ * @package  Validator
+ * @author   Alexander Purr <purr@ub.uni-leipzig.de>
+ * @license  http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @link     https://vufind.org/wiki/development Wiki
+ */
 class SubitoPartialCopyPageOrder extends AbstractValidator
 {
     use SubitoPartialCopyPageRangeValidatorTrait;
@@ -32,11 +48,18 @@ class SubitoPartialCopyPageOrder extends AbstractValidator
         self::PAGES_ORDER => "acquisition_error_page_order",
     ];
 
-    public function isValid($value)
+    /**
+     * Validate if given page range is ordered correctly
+     *
+     * @param string $value From to page range
+     *
+     * @return bool
+     */
+    public function isValid(string $value) : bool
     {
-        $this->extractPages($value);
+        $this->_extractPages($value);
 
-        if ($this->pageStart > $this->pageEnd) {
+        if ($this->_pageStart > $this->_pageEnd) {
             $this->error(self::PAGES_ORDER);
             return false;
         } else {
diff --git a/module/fid/src/Validator/SubitoPartialCopyPageRangeValidatorTrait.php b/module/fid/src/Validator/SubitoPartialCopyPageRangeValidatorTrait.php
index ee91dbc6a10d4366d49b771cd921d22493defd55..87a4551c814075bf7038260b99971a74e4695369 100644
--- a/module/fid/src/Validator/SubitoPartialCopyPageRangeValidatorTrait.php
+++ b/module/fid/src/Validator/SubitoPartialCopyPageRangeValidatorTrait.php
@@ -1,7 +1,11 @@
 <?php
 /**
+ * Subito partial copy page range validator trait
+ *
  * Copyright (C) 2020 Leipzig University Library
  *
+ * PHP Version 7
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
@@ -15,23 +19,42 @@
  * with this program; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
- * @author  Alexander Purr <purr@ub.uni-leipzig.de>
- * @license http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @category VuFind
+ * @package  Validator
+ * @author   Alexander Purr <purr@ub.uni-leipzig.de>
+ * @license  http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @link     https://vufind.org/wiki/development Wiki
  */
 namespace fid\Validator;
 
 use fid\Controller\RecordController;
 
+/**
+ * Subito partial copy page range validator trait
+ *
+ * @category VuFind
+ * @package  Validator
+ * @author   Alexander Purr <purr@ub.uni-leipzig.de>
+ * @license  http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @link     https://vufind.org/wiki/development Wiki
+ */
 trait SubitoPartialCopyPageRangeValidatorTrait
 {
-    private $pageStart = null;
+    private $_pageStart = null;
 
-    private $pageEnd = null;
+    private $_pageEnd = null;
 
-    private function extractPages($value)
+    /**
+     * Extract start and end page of a page range (string like '12-123')
+     *
+     * @param string $value From to page range
+     *
+     * @return void
+     */
+    private function _extractPages(string $value)
     {
         preg_match(RecordController::PAGE_RANGE_PATTERN, $value, $matches);
-        $this->pageStart = (int)$matches[1];
-        $this->pageEnd = (int)$matches[2];
+        $this->_pageStart = (int)$matches[1];
+        $this->_pageEnd = (int)$matches[2];
     }
 }
diff --git a/module/fid/src/Validator/SubitoPartialCopyPageSelection.php b/module/fid/src/Validator/SubitoPartialCopyPageSelection.php
index 00f5be4679e4718861cef7d83cde59568965f266..41dabd58c0b7003d536ff148900069e4d8269ec2 100644
--- a/module/fid/src/Validator/SubitoPartialCopyPageSelection.php
+++ b/module/fid/src/Validator/SubitoPartialCopyPageSelection.php
@@ -1,7 +1,11 @@
 <?php
 /**
+ * Subito partial copy page selection validator
+ *
  * Copyright (C) 2020 Leipzig University Library
  *
+ * PHP Version 7
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
@@ -15,13 +19,25 @@
  * with this program; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
- * @author  Alexander Purr <purr@ub.uni-leipzig.de>
- * @license http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @category VuFind
+ * @package  Validator
+ * @author   Alexander Purr <purr@ub.uni-leipzig.de>
+ * @license  http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @link     https://vufind.org/wiki/development Wiki
  */
 namespace fid\Validator;
 
 use Zend\Validator\AbstractValidator;
 
+/**
+ * Subito partial copy page selection validator
+ *
+ * @category VuFind
+ * @package  Validator
+ * @author   Alexander Purr <purr@ub.uni-leipzig.de>
+ * @license  http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @link     https://vufind.org/wiki/development Wiki
+ */
 class SubitoPartialCopyPageSelection extends AbstractValidator
 {
     use SubitoPartialCopyPageRangeValidatorTrait;
@@ -39,15 +55,26 @@ class SubitoPartialCopyPageSelection extends AbstractValidator
         'percentagedLimit'  => 10
     ];
 
-    public function isValid($value)
+    /**
+     * Validate if given page selection does not exceed percentaged limit of a record
+     *
+     * @param string $value From to page range
+     *
+     * @return bool
+     */
+    public function isValid(string $value) : bool
     {
         if ($this->options['numberPages'] == null) {
             return false;
         }
-        $this->extractPages($value);
+        $this->_extractPages($value);
 
-        $selection = $this->pageEnd - $this->pageStart;
-        $permittedSelection = (($this->options['percentagedLimit'] / 100) * $this->options['numberPages']) + $this->options['tolerancePages'];
+        $selection = $this->_pageEnd - $this->_pageStart;
+        $permittedSelection = (
+                ($this->options['percentagedLimit'] / 100)
+                * $this->options['numberPages']
+                )
+            + $this->options['tolerancePages'];
         if ($selection > $permittedSelection) {
             $this->error(self::PAGE_SELECTION);
             return false;