Context:

Referenced when introducing the guest Ian McGregor, noting that he previously wrote a book about Checkpoint Charlie and appeared on a podcast about the Berlin Wall

Context:

Ian McGregor is introduced as the guest author of this book about the Berlin Wall. The hosts explicitly state 'we have Ian McGregor, the author of Checkpoint Charlie, book about the Berlin Wall with us' and later recommend it saying 'anyone who wants to know more about the Berlin wall, can't recommend it highly enough.'