[Correspondence of A.B. Hart, Herman Hagedorn, and others, relating to contributions to be published by the Vigilantes, 1917-1918Albert Bushnell Hart, Morse, John T. Jr, Hermann HagedornOpen the Tome
Pipeline to RussiaAlexander B. Dolitsky, Dan Hagedorn, John Haile Cloe, Victor D. Glazkov · First published 2016Open the Tome
North American F-51 Mustangs in Latin American air force serviceJohn Dienst, Dan Hagedorn · First published 1986Open the Tome
