I see lot of people disputing about the source and all that, But think about it and try these astrologers, it is 100% accurate. And also there are different versions available in the same town (Vaitheeswarankoil) there are infact 7 of them written by 7 different Maharishis. For just to know the accuracy I try 2 diff versions, to my amassment only the language used was slightly deferent, but effectively predicted almost every thing. Even I was told about the age at which I would be married and some indications of the girl’s family and name were also given. All this nearly seven years before my marriage and I am still amazed at this.
I referred many of my friends and every one of them had amazing stories to tell. One of them told that he was told about his age at which he is visiting this astrologer and name of a friend who accompany him, all this with nothing but his thumb impression. Most starling of them is reference of names of friends and family.
So there is nothing to dispute in there existence, But you can always dispute there source. Once I had discussion a with a learned astrologer about this and he opinioned that the existing copies may be duplicates made from the ancient texts and that is why so many of them have them. And so lets not dispute them with our inability to locate there exact source, but find truth in what they are.And also be beware of con men who would sell you any thing but truth. Ask the locals of the town (Vaitheeswarankoil) before you vist any of the astrologers.