Genealogy research in England frequently results in the need to find source information about royalty. There are so many genealogical posting errors on the web, you have to prove your research with reliable sources several times before you dare post any information yourself.
One of the books I use for reference is “The Historic Peerage of England by Sir Nicholas Harris G.C.M.G.
Thanks to Google Books, the book is available online for all of us to access at any time and on any day of the week.