Open question: Settled gross-receipts of the Oberseiten-400?

I know that there is a web site with the Spitzen400 settled gross-receipts for individual income tax returns. White someone, if there is a way to find out how those incomes was acquired? I do not speak, personal information about these people find out. E.G. you let say us the point-settled Bruttoeinkunft were $1 million. Would it give a way to find out that money was acquired, by saying we a book wrote?