Sigma Models And The ADHM Construction Of Instantons
  This paper is devoted to the construction of a family of linear sigma models with $(0,4)$ supersymmetry which should flow in the infrared to the stringy version of Yang-Mills instantons on ${\bf R}^4$. The family depends on the full set of expected parameters and is obtained by using the data that appear in the ADHM construction of instantons. 
Edward Witten