Syncing non-Amazon purchased eBooks between Kindle, iPad, and iPhone

I have an Amazon Kindle Keyboard, an iPhone, and an iPad. I have purchased a load of eBooks from the publisher, O'Reilly, and have downloaded them on to the Kindle via USB. I note these do not show up in my Kindle account on the Amazon website, and nor do they show up on my iPhone's or iPad's Kindle apps. Is it possible to put non-Amazon eBook purchases into my Kindle account so they show up on all my devices?