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Johann Leopold, Hereditary Prince of Saxe-Coburg and Gotha (Johann Leopold William Albert Ferdinand Victor; 2 August 1906 -- 4 May 1972) was the eldest son of Charles Edward, Duke of Saxe-Coburg and Gotha and Princess Victoria Adelaide of Schleswig-Holstein-Sonderburg-Glucksburg.
Who is the mother of Johann Leopold, Hereditary Prince of Saxe-Coburg and Gotha?