Eadwulf IV, king of Northumbria - Eadwulf IV, King of Northumbria

There is a king list for Northumbria here:

https://en.wikipedia.org/wiki/List_of_monarchs_of_Northumbria

This person does not appear to be on it, along with most of the people here listed as kings.

There is another listing here:

http://www.1066.co.nz/Mosaic%20DVD/whoswho/text/List_of_monarchs_of...

This link lists the ancestors of Uhtred the Bold as earls, not kings. I suspect the others listed here, if the existed were earls and not kings.

Please confirm.