diff --git a/include/library.h b/include/library.h
index b56dab896..4a859086d 100644
--- a/include/library.h
+++ b/include/library.h
@@ -122,6 +122,9 @@ class Library
   std::map<std::string, std::shared_ptr<Reader>> m_readers;
   std::vector<kiwix::Bookmark> m_bookmarks;
 
+ public:
+  typedef std::vector<std::string> BookIdCollection;
+
  public:
   Library();
   ~Library();
@@ -224,7 +227,7 @@ class Library
    *
    * @return A list of book ids.
    */
-  std::vector<std::string> getBooksIds();
+  BookIdCollection getBooksIds();
 
   /**
    * Filter the library and generate a new one with the keep elements.
@@ -234,7 +237,7 @@ class Library
    * @param search List only books with search in the title or description.
    * @return The list of bookIds corresponding to the query.
    */
-  DEPRECATED std::vector<std::string> filter(const std::string& search);
+  DEPRECATED BookIdCollection filter(const std::string& search);
 
 
   /**
@@ -243,7 +246,7 @@ class Library
    * @param filter The filter to use.
    * @return The list of bookIds corresponding to the filter.
    */
-  std::vector<std::string> filter(const Filter& filter);
+  BookIdCollection filter(const Filter& filter);
 
 
   /**
@@ -253,7 +256,7 @@ class Library
    * @param comparator how to sort the books
    * @return The sorted list of books
    */
-  void sort(std::vector<std::string>& bookIds, supportedListSortBy sortBy, bool ascending);
+  void sort(BookIdCollection& bookIds, supportedListSortBy sortBy, bool ascending);
 
   /**
    * List books in the library.
@@ -277,7 +280,7 @@ class Library
    *                Set to 0 to cancel this filter.
    * @return The list of bookIds corresponding to the query.
    */
-  DEPRECATED std::vector<std::string> listBooksIds(
+  DEPRECATED BookIdCollection listBooksIds(
     int supportedListMode = ALL,
     supportedListSortBy sortBy = UNSORTED,
     const std::string& search = "",
diff --git a/src/library.cpp b/src/library.cpp
index b16c4b9d6..920d93eda 100644
--- a/src/library.cpp
+++ b/src/library.cpp
@@ -211,9 +211,9 @@ const std::vector<kiwix::Bookmark> Library::getBookmarks(bool onlyValidBookmarks
   return validBookmarks;
 }
 
-std::vector<std::string> Library::getBooksIds()
+Library::BookIdCollection Library::getBooksIds()
 {
-  std::vector<std::string> bookIds;
+  BookIdCollection bookIds;
 
   for (auto& pair: m_books) {
     bookIds.push_back(pair.first);
@@ -222,7 +222,7 @@ std::vector<std::string> Library::getBooksIds()
   return bookIds;
 }
 
-std::vector<std::string> Library::filter(const std::string& search)
+Library::BookIdCollection Library::filter(const std::string& search)
 {
   if (search.empty()) {
     return getBooksIds();
@@ -232,16 +232,16 @@ std::vector<std::string> Library::filter(const std::string& search)
 }
 
 
-std::vector<std::string> Library::filter(const Filter& filter)
+Library::BookIdCollection Library::filter(const Filter& filter)
 {
-  std::vector<std::string> bookIds;
+  BookIdCollection bookIds;
   for(auto& pair:m_books) {
     if(filter.acceptByQueryOnly(pair.second)) {
       bookIds.push_back(pair.first);
     }
   }
 
-  std::vector<std::string> result;
+  BookIdCollection result;
   for(auto id : bookIds) {
     if(filter.acceptByNonQueryCriteria(m_books[id])) {
       result.push_back(id);
@@ -309,7 +309,7 @@ std::string Comparator<PUBLISHER>::get_key(const std::string& id)
   return lib->getBookById(id).getPublisher();
 }
 
-void Library::sort(std::vector<std::string>& bookIds, supportedListSortBy sort, bool ascending)
+void Library::sort(BookIdCollection& bookIds, supportedListSortBy sort, bool ascending)
 {
   switch(sort) {
     case TITLE:
@@ -333,7 +333,7 @@ void Library::sort(std::vector<std::string>& bookIds, supportedListSortBy sort,
 }
 
 
-std::vector<std::string> Library::listBooksIds(
+Library::BookIdCollection Library::listBooksIds(
     int mode,
     supportedListSortBy sortBy,
     const std::string& search,