example1.cs

public static List<User> All() {
  return PersistentObject.INSTANCE.Fetch(
    new Dictionary<string, object>(),
      "users",
      typeof(Book)
  ).ConvertAll(x => (Book)x);
}

example2.cs

public static List<User> All() {
  return PersistentObject.INSTANCE.Fetch(
    new Dictionary<string, object>(),
      "users",
      typeof(this)
  ).ConvertAll(x => (Book)x);
}