because
Herbert Hover was not a president, Herbert Hoover was.
Dow Hover died in 1990.
Robert Hover died on February 15, 2013, in Warren, Rhode Island, USA.
Herbert Clark Hoover is the full name of the United States 31 president and the 3rd Untied States Secretary of Commerce. He was also a Quaker and the only president from Iowa.
Herbert Sebald died in 1974.
Herbert Aitken died in 1961.
Herbert Avram died in 2006.
Herbert Seifert died in 1996.
Herbert Sedgwick died in 1957.
Herbert Blankenhorn died in 1991.
Herbert Sumsion died in 1995.
Herbert Barbee died in 1936.