It is not possible for us to read these books currently because they are in the possession of Imam Mahdi (A) only. When Imam Mahdi returns, perhaps he might share them - God knows best.
Sometimes "jafr" is used for other things, or other books are circulated which are said to be the book of Jafr, but these are not the same as the Jafr described in hadith as in the hands of the Imams (A). If they are attributed to the Imams, it is a false attribution.