Washington (CNN) Subpoenas served on the Trump Organization and a dozen related business entities by the attorneys general of the District of Columbia and Maryland on Wednesday include demands for tax documents -- raising the possibility that President Donald Trump's corporate returns could eventually be made public.

While the subpoenas don't ask for the President's personal tax returns, tax documents related to his businesses could begin to fill out a picture of the President's own finances by providing information about his main income sources.

Trump has not released his personal tax returns, which was a standard practice among past presidents and candidates until Trump.

The office of District of Columbia Attorney General Karl Racine said Wednesday that it "can confirm that all of the Trump Organization entities have been served."

Additionally, subpoenas are being served to the state of Maine, the attorney general's office said. The subpoena issued to the state of Maine's Department of Administrative and Financial Services asks for information regarding any payments from the state made to Trump's hotel or BLT Prime restaurant after the 2016 election, according to court documents.

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