Off topic, but what an extraordinary book that is! The final chapter ranks among the most moving writing I can remember.
As for Limbo, it was a difficult place to imagine when I was a child. It didn't close until 2007, when
I was an adult. Prior to that, there was no exiting Limbo until the Final Judgement.
See the "Tibetan Book of the Dead" for rites and rituals in the bardo.