what is his musical style?
According to Nelson Riddle "His voice has a very strident, insistent sound in the top register, a smooth lyrical sound in the middle register, and a very tender sound in the low."
Frank Sinatra
His voice has a very strident, insistent sound in the top register, a smooth lyrical sound in the middle register, and a very tender sound in the low. 
who said the greatest thing you'll ever learn It is the last line of a song written by Eden Ahbez. where is the above mentioned writer from? He was born in Brooklyn ,New York. what is his famous work? For composing the song "Nature Boy".. when was this song composed? UNANSWERABLE what are some versions of this song? The Dick Haymes recording, a version by Frank Sinatra, another version by Bobby Darin and many more. where was the second mentioned person born? 415 Monroe Street in Hoboken, New Jersey. where did he study? UNANSWERABLE who were his parents? Natalina "Dolly" Garaventa and Antonino Martino "Marty" Sinatra. what were their professions? His mother was a midwife and his father was a bantamweight boxer in the beginning and later worked in the Hoboken Fire Department. how did he start his musical career? Upon joining a local singing group called the 3 Flashes.
wiki:7687202
Frank Sinatra [SEP] Artistry
After a period of performing, Sinatra tired of singing a certain set of songs and was always looking for talented new songwriters and composers to work with. Once he found ones that he liked, he actively sought to work with them as often as he could, and made friends with many of them. He once told Sammy Cahn, who wrote songs for "Anchors Aweigh", "if you're not there Monday, I'm not there Monday". Over the years he recorded 87 of Cahn's songs, of which 24 were composed by Jule Styne, and 43 by Jimmy Van Heusen. The Cahn-Styne partnership lasted from 1942 until 1954, when Van Heusen succeeded him as Sinatra's main composer.