MindWare makes many extreme dot-to-dot printables, which are available on its website and to purchase as books. Extreme dot-to-dot printables are also available on education and game websites.
MindWare has published a book of extreme dot-to-dot puzzles that result in images of animals. The exercises promise to work both the right and left brains. The puzzles range from 300 to over 1,400 dots, and they're designed to encourage mapping skills. The book is available on MindWare.com, and the site also allows users to download free sample pages, as of March 2015.
Amazon.com also sells the animal book, in addition to other MindWare extreme dot-to-dot books. These include themes such as "Around the USA," "Animals 2," and "Legends and Lore." Amazon.com sometimes offers a slight discount and free shipping, depending on the seller.
ConnectTheDots.com features over 100 pages of hard connect the dots puzzles. The pages feature many themes, ranging from super heroes to aquatic scenes. The pages are free to download and print.
EdHelper is another website that offers printable extreme dot-to-dot puzzles. The pages are organized into themes, such as holidays, seasons and educational subjects. EdHelper.com is not a free site though. Users must subscribe with a paid membership. Schools enjoy a discount on the membership depending on the number of subscribers.