+ * Return a list of bookmark matching provided period of time.
+ * It also update directly previous and next date outside of given period found in the datastore.
+ *
+ * @param \DateTimeInterface $from Starting date.
+ * @param \DateTimeInterface $to Ending date.
+ * @param \DateTimeInterface|null $previous (by reference) updated with first created date found before $from.
+ * @param \DateTimeInterface|null $next (by reference) updated with first created date found after $to.