Historian Darren Reid of Coventry University states it is difficult for historians to document anything with certainty since Native Americans, as a non-literate society, did not produce the written sources upon which historians rely. Instead, what is cited as Native American usage was generally attributed to them by European writers. Any use of "red" in its various forms, including redskin, by Native Americans to refer to themselves reflected their need to use the language of the times in order to be understood by Europeans.