Check here to get Free Kindle copy of vSphere 5.0 Clustering Deepdive and vSphere 4.1 HA and DRS Deepdive

Yes, it's not a joke, it's completely free for 48 hours offer, Wednesday June the 5th and Thursday June the 6th. In US Kindle Store you can download the kindle copy of both these books for free. Duncan Epping (the author of these ebook) put this promotion on his blog on 28 May

So don't forget either Wednesday June the 5th or Thursday June the 6th, it might be the only time this year it is on promo.
Source: http://www.yellow-bricks.com/2013/05/28/free-kindle-copy-of-vsphere-5-0-clustering-deepdive/