Question

[1] Many people have argued that nothing could justify the president’s use of the atomic bomb because it killed so many innocent civilians. [2] Truman himself refused to drop a third atomic bomb on Japan because he was horrified by the death and devastation it had caused. [3] However, he never regretted his decision to use it in the first place. [4] Using the bomb brought an immediate end to a war that might have gone on for months or even years longer. [5] It is impossible to put a number on how many more deaths the continuing war might have caused, but there are indications. [6] Millions had already died in the Pacific theater. [7] Whenever US troops invaded an island, they knew the fight was to the death. [8] In the battle for Okinawa alone, there had been almost 50,000 US casualties, while Japan had suffered some 90,000 military deaths and at least 100,000 civilian deaths. [9] With his decision, Truman put an end to the slaughter. Which of these sentences should be followed by a citation?

Answer 1

The sentences that should be followed by a citation are sentences 2, 7 and 8. Here are the reasons.
 
[2] Truman himself refused to drop a third atomic bomb on Japan because he was horrified by the death and devastation it had caused.
→Because the author is citing a person's view about the bomb.

[7] Whenever US troops invaded an island, they knew the fight was to the death.
→Because the author of this work is citing a military force that concluded that when US is involved, it is to the death.

[8] In the battle for Okinawa alone, there had been almost 50,000 US casualties, while Japan had suffered some 90,000 military deaths and at least 100,000 civilian deaths. 
→Because the author is citing number of casualties that are recorded in real life.