I picked up some B&SR books at the Springfield Show. Two are titled "Bridgton, Maine - It's scenic Lakes, Mountains and Summer Delights" The booklets were published by the B&SR to bring tourists to the Bridgton area. They were printed around 1899 - 1900 judging by the Harrison Branch looking new. There are many photos of the railroad, guest houses, lakes, and industry. The booklets have different covers but similar photos and text.
Another book is titled "My First Sixty Years in Harrison, Maine" by Ernest E. Ward, published in 1966. I've heard Dana talk about this book, it's a good short history book with a 29 page section on the B&SR. Mr. Ward was a brakeman for a number of years and has good descriptions of his years on the railroad. There are other chapters on life in Bridgton in the early 20th century.