Associated Press Stylebook 2015 and Briefing on Media Law The must-have manual for journalists and business owners. Or get the online subscription:
On Writing Well: The Classic Guide to Writing Nonfiction Every writer needs "On Writing Well" to improve his or her writing. Great tips. I still have my Third Edition.
On Writing: 10th Anniversary Edition: A Memoir of the Craft Awesome stories on Stephen King's life as a writer, with writing tips too! Haven't read this latest edition, but the 2000 edition is great.