Which occurred first, Chetnik units attacked the Partisans or Partisans formed the 1st Proletarian Assault Brigade?
return Chetnik units attacked the  Partisans ;return Partisans formed the  1st Proletarian Assault Brigade ;return when  was  #1 ;return when  was  #2 ;return which is the  lowest of #3 ,  #4
['select', 'select', 'project', 'project', 'comparison']