L. Sprague deCamp 
Undesired Princess [EPUB ebook] 

The Undesired Princess Rollin Hobart thought he was a logical, sensible man – until he was transported to a world that was perfectly logical but not sensible in the least.The Enchanted Bunny Joe Johnson thought he had his hands full ghostwriting a Senators memoirs – but that was before he fell into the middle of a fairy tale, complete with wizard and fire-breathing dragon.Two reluctant heroes using their modern knowledge but finding that things don’t work quite the way they’re used to. But they’ve got to try, because nobody else can save the world – and unless Hobart and Joe succeed they and their new friends are going to be horribly and realistically dead.