Are there any references to Kavach in Vedic literature?
The individual set of mystical numbers and use of gemstones do come from classical literature. The books written in fifth century, too, find mention and benefits of these. In 1991 we were using the mystical numbers of individual planets for raising the strength of the concerned planets for removing obstructions for the natives, for dealing with the health problems, for cutting down the delay in marriage, etc. etc. While the current problem of the native used to be tackled this way, in subsequent sub periods the natives encountered some other problems. Our team members experimenting the utility of these included (i) Mr. R K Chadha, who is an engineer and an MBA by profession and had been interested in astrology since mid sixties and had attended a regular course in astrology in Bhartiaya Vidya Bhavan even in 1968; (ii) Dr. Mrs. K Batra, a gynecologist, who was monitoring the impacts on the chronic patients and on prime sterility cases and (iii) Mr. Kumar Jhuraney, a businessman deeply i