What may have happened if the sub shot the nuke, in the Cuban Missile Crisis

How should the student cite this source using mla citation format?

Which areas where seperated by the iron curtain

Is the weather changing? consider the data of severe weather that includes tornadoes occurring throughout the u. s. over the last four years. compare the severe weather for the last three years. then compare the first three months of 2017 with that data. based on previous years, what might the prediction be for weather during 2017?