Christopher Morley 
Parnassus on Wheels [PDF ebook] 

Parnassus on Wheels is a novel by Christopher Morley, published in 1917. The Parnassus of the title refers to the mountain that was the home of the Muses in Greek mythology. In the story, Roger Mifflin sells his traveling bookshop to Helen Mc Gill, who tires of looking after Andrew, her ailing brother. Christopher Morley later continued the story of Roger Mifflin in his 1919 novel The Haunted Bookshop.