I am working with JPA now quite some time, but always found that the documentation is not very detailed for such an important subject. Good to find some coherent information and surprising to me that this presentation has only 1851views on Slideshare. Slideshare is actually a really good resource for  quality in-depth information on various technical subjects.

Think about it: its most likely a presentation that was actually presented in front of some people. The presenter has most likely done research on the topic, is experienced on the subject or at least tried out what he is presenting. Hence as a rule of thumb I assume that there is a higher probability of quality and researched information than you find on random places on the Internet.

Its a pity that those presentations often do not to have such a good ranking in the Google searches.

Another good resource in the last couple of months became stackoverflow.com. They made a few things right to encourage and control good answers – and questions. SO would never have the success if it would not have the social status / name branding aspect built into it. Contrary to Slideshare, here Google is up-to-date with their indexing.