Which of Ken's book should I read to best prepare for the PSM I?

Whoops. The second book is titled Agile Software Development With Scrum.

From my experience, for PSM I you don't need any book to read accept Scrum guide and lots of practice on open assessments.

That's what I've been reading Ankit, however, it is not entirely accurate. For example the guide has nothing on burndown charts, yet I hear there are at least a few questions on this topic. I'd like to go the extra mile to prepare. Anyone have a recomendation between these two books by Ken? Is one preferred over the other? Thanks.

Ankit is right: the Scrum guide is all you need, and it should trump any other source when it comes to the PSM I.

Regarding burndown charts, it's not entirely accurate to say that the guide has nothing:

"Various projective practices upon trending have been used to forecast progress, like burn-downs, burn-ups, or cumulative flows. These have proven useful. However, these do not replace the importance of empiricism."

Keep that in mind and you should be fine.

Thanks. I passed! Note that there was one question about burndown charts and the info in the Scrum guide would NOT have been enough to answer the question.  It was a specific question about a specific part of the burndown chart and what it meant. Thanks to another poster providing advice to do some additional research on burndown charts I'm pretty sure I got it right.

Also I read Agile Project Management With Scrum by Ken and it gave a TON of real world actual examples of scrum in use. This was also a big help in preparing me and making me feel more confident to pass the test.

Still curious to know the difference between the two books. Guess I'll have to read Agile Software Development With Scrum to find out.

Scrum on!

Cool Congratulations!! PSM I does contain some burndown chart question but those are basic and straightforward, if you simply know what burndown is then you can answer them.

Another area that I found lacking in the Guide was around larger projects with multiple scrums teams.  Questions around dependencies, make-up and organization but there were some very detailed questions on the PSM1 test.

That's I recommend everyone to do all open assessments on Scrum.org and not only Scrum master one, Nexus open would give some insight for multiple Scrum team questions.