His works include Banner in the Sky, which was a book based on the true story of the first climbing of the Matterhorn (it was filmed in Switzerland as Third Man on the Mountain), and The White Tower (which would star Glenn Ford and Lloyd Bridges).
In his late 20's, after a discouraging lack of success as a theatrical producer, in New York, he undertook a journey from Lima to the Atlantic.
Ullman was the ghost writer for Tenzing Norgay's 1955 autobiography Man of Everest (originally published as Tiger of the Snows)[3] and for John Harlin's biography Straight Up.
Beyond his mountaineering books, he wrote "Where the Bong Tree Grows," an account of a year he spent travelling through some of the most remote islands of the South Pacific.
On May 1, 1963 Jim Whittaker was the first American to reach the summit with Nawang Gombu, a nephew of Tenzing Norgay.