Not only this but his account is made less reliable as it was written 16 years after the event and therefore his memory may have been distorted. Fritz Hesse was a journalist working for the Nazis at the time of Kristallnacht, so he is more likely to defend the Nazi Party. However Hesse view given in Source A completely contradicts the idea of him defending his party. This may be because in 1954 the Nazi party was finished and he finally decided the truth could now be told. So in fact his account is more reliable than first thought as he could now speak out the true events of November 9th.
Source B is a secret report prepared by the Nazi Party Supreme Court after the events of Kristallnacht. This source states that the German people were to blame for Kristallnacht in a spontaneous attack on Jewish homes. As this report was prepared and published by the Nazis it is likely that they may have twisted the truth and pushed the blame onto the people to save themselves from blame. The fact that the report was published after the events of Kristallnacht further supports the sources unreliability as it seems as a cover up.
Also as the source suggests that such demonstrations were not to be organized by the party, but neither were they to be discouraged if they started spontaneously, suggests the fact that the Nazis did not mind any spontaneous attacks showing their hatred for the Jews, thus giving them motive for the brutal acts of Kristallnacht . The source itself would not have changed as it was an official document published by the Nazis. Finally the very fact it was a secret document suggest the Nazis were trying to hide something.
Whilst both sources give explanations of what happened on the night of Kristallnacht, they both have their different uses to a Historian studying the event. Source A may well have been a little distorted over the years but the fact that that Hesse was able to tell the truth helps create an unbiased view of the events. On the other hand source B is completely unreliable as its clear that it has been twisted and there is evidence in the text that the Nazis did not care about the supposed rioting. Source B is good for historians to see who was to blame, simply because of where the source came from and how it was manipulated.
We know this is what the source actually said so we trust it and because of the clear manipulation made by the Nazis to the source, it is clear to see their views on who was to blame, thus telling us what the Nazis true actions were. Meanwhile Source A simply tells us about the events of Kristallnacht without any bias and in the source and not in the provenance. Ultimately both would offer good insights into the events of Kristallnacht and who was to blame through working out the opposite from the unreliable source (Source B) or simply looking at the fairly reliable information in the source itself ( Source A).