RAGING TWENTIES is distributed both by Ingram, the largest U.S. distributor (hardcover) and Amazon's Kindle Direct Publishing (paperback and Kindle formats). Accordingly, it is available from almost all online bookstores.
The Wikipedia ISBN pages for the paperback and hardcover provides a super comprehensive list of everywhere that you can possibly find the book, including libraries, bookshops, and online resources. Indeed, it is so comprehensive that it's a bit hard to use, so here are a few highlights.
Amazon is fast. Paperback on Amazon.com (or .ae, .au, .br, .ca, .cn, .de, .es, .fr, .in, .it, .jp, .mx, .nl, .sa, .se, .sg, .tr, .uk). Their subsidiary Bookdepository.com has free delivery worldwide - hardcover and paperback.
Barnesandnoble.com is familiar to many in the US - paperback
Blackwell's similarly for the UK - paperback
Bookshop.org gets good word of mouth and donates to local booksellers. - paperback
Price comparison sites like Bookfinder can be helpful - paperback
If you want your local bookseller or library to buy a copy, tell them to order from Ingram or Ingram International. The ISBN for the paperback is 9781608882205 and for the hardcover is 9781608882335.
If all else fails, you can order direct from the publisher, Nimble Books - email sales at nimblebooks doht com. Be aware that the international shipping options available to us are likely more expensive than those available to huge companies!