How many months after Romanian forces established control over Bessarabia did Romania formally attach Bessarabia?
return Romanian forces established controls over Bessarabia  ;return Romania did formally attach Bessarabia  ;return when  was  #1 ;return when  was  #2 ;return difference of #3 and  #4 in  months
['select', 'select', 'project', 'project', 'arithmetic']