diff --git a/core/modules/book/src/BookManager.php b/core/modules/book/src/BookManager.php
index 1b354a4..4f4123c 100644
--- a/core/modules/book/src/BookManager.php
+++ b/core/modules/book/src/BookManager.php
@@ -583,7 +583,7 @@ protected function buildItems(array $tree) {
    * Builds a book tree, translates links, and checks access.
    *
    * @param int $bid
-   *   The ID of the book that are used to build the tree for.
+   *   The Book ID to find links for.
    * @param array $parameters
    *   (optional) An associative array of build parameters. Possible keys:
    *   - expanded: An array of parent link IDs to return only book links that
@@ -618,21 +618,21 @@ protected function bookTreeBuild($bid, array $parameters = array()) {
    * _menu_tree_check_access() needs to be invoked afterwards.
    *
    * @param int $bid
-   *   The ID of the book that are used to build the tree for.
+   *   The Book ID to find links for.
    * @param array $parameters
    *   (optional) An associative array of build parameters. Possible keys:
    *   - expanded: An array of parent link IDs to return only book links that
    *     are children of one of the parent link IDs in this list. If empty,
    *     the whole outline is built, unless 'only_active_trail' is TRUE.
-   *   - active_trail: An array of node IDs, representing the coordinates of the
-   *     active book link.
+   *   - active_trail: An array of node IDs, representing the currently active
+   *     book link.
    *   - only_active_trail: Whether to only return links that are in the active
    *     trail. This option is ignored if 'expanded' is non-empty.
    *   - min_depth: The minimum depth of book links in the resulting tree.
    *     Defaults to 1, which is to build the whole tree for the book.
    *   - max_depth: The maximum depth of book links in the resulting tree.
    *   - conditions: An associative array of custom database select query
-   *     condition key/value pairs; see _menu_build_tree() for actual query.
+   *     condition key/value pairs; see _menu_build_tree() for the actual query.
    *
    * @return array
    *   An array with links representing the tree structure of a book.
@@ -951,7 +951,7 @@ public function bookTreeCheckAccess(&$tree, $node_links = array()) {
    * Sorts the menu tree and recursively checks access for each item.
    *
    * @param array $tree
-   *   The book tree which have to operate on.
+   *   The book tree to operate on.
    */
   protected function doBookTreeCheckAccess(&$tree) {
     $new_tree = array();