Google and Barnes & Noble are joining forces to tackle their mutual rival Amazon, zeroing in on a service that Amazon has long dominated: the fast, cheap delivery of books. Starting on Thursday, book buyers in Manhattan, West Los Angeles and the San Francisco Bay Area will be able to get same-day deliveries from local Barnes & Noble stores through Google Shopping Express, Google’s fledgling online shopping and delivery service. Google Shopping, which began operations about a year ago, allows online shoppers to order products from stores like Costco, Walgreens, Staples and Target, and have them delivered to their doors within hours. The partnership could help Barnes & Noble make inroads into online sales when its brick-and-mortar business remains stagnant.