public static CurrentPageManager getInstance() {
    if (singleton == null) {
      synchronized (CurrentPageManager.class) {
        if (singleton == null) {
          CurrentPageManager instance = new CurrentPageManager();
          instance.currentBibleVerse = new CurrentBibleVerse();
          instance.currentBiblePage = new CurrentBiblePage(instance.currentBibleVerse);
          instance.currentCommentaryPage = new CurrentCommentaryPage(instance.currentBibleVerse);
          instance.currentMyNotePage = new CurrentMyNotePage(instance.currentBibleVerse);

          instance.currentDictionaryPage = new CurrentDictionaryPage();
          instance.currentGeneralBookPage = new CurrentGeneralBookPage();

          instance.currentDisplayedPage = instance.currentBiblePage;
          singleton = instance;
        }
      }
    }
    return singleton;
  }