Ernest Albert Spongberg, Jenny Lind (1920). “The life of Jenny Lind, Oct. 6, 1820-Nov. 2, 1887: a compilation from various sources, in commemoration of the centenary of her birth”
Dr. David J. Lieberman, Ph.D. (2010). “Make Peace With Anyone: Breakthrough Strategies to Quickly End Any Conflict, Feud, or Estrangement”, p.194, St. Martin's Press