I just found this on Jerry Bails' Who's Who of American Comic Books:
Print Media (non-comics)
Writer: Novels: 1978/81/83 [comics tie-ins] Superman '78/81; Miracle Monday '81; Batman '83
To see this, go to ==>
Who's Who <== and search for MAGGIN. The above text is about a dozen lines from the top.
I also found this reference on Barnes & Noble:
http://search.barnesandnoble.com/booksearch/isbnInquiry.asp?z=y&EAN=9780671475659&itm=8Who's Who says this is a novel. B&N says it is for "Young Adult". Does anyone out there have this book? Does it really exist?