"Por una Cabeza" is an tango song with music and lyrics written in 1935 by Carlos Gardel and Alfredo Le Pera respectively. It has appeared in numerous movies, most famously in Scene of a Woman with Al Pacino, but also, for example, in Schindler's List.
Tango (Por Una Cabeza)
(Solo Violin with Piano Reduction). Composed by Carlos Gardel and Alfredo Le Pera. Arranged by John Williams. For Violin, Piano Accompaniment. John Williams Signature Edition - Strings. 8 pages. Published by Hal Leonard (HL.842193).