In my line of work, you need to read a great deal of books about Theodore Roosevelt. My current undertaking is called Lion in the White House, a life of Theodore Roosevelt by Aida D. Donald. Called a “short Biography” this book is a well written overview of TR. Filled with images as well as interesting stories, this is a great way to get “your feet wet” about the man who was called “the Lion” by his children. With a man as complex as Roosevelt, I recommend that you start out by reading a book like this one, and then focus in on the parts of TR’s life that interest you.
I have many, many books that outline the history of Roosevelt in detail and many are very good. I love to shop antique stores and find old volumes that have been out of print that may give me added insights into the complex man many know as “Teddy”. This has led me to books on his daughter Alice, herself an interesting character and on Edith, his wife, who was as important in his career (as any man with a good wife knows). I recently found a book focused on TR at Oyster Bay at his home which details his family life, a great find and a perfect glimpse into the man when he was away from the White House.
I spend a great deal of time on the internet as well and find that many of the stories about TR have been frankly poorly copied or altogether incorrect. If you read a fact stated on my web site, I have at least three volumes of data to support the statement. However, there is an important statement I learned long ago “History is lies agreed upon”. So while I have supporting evidence, I always take into account that the evidence is only as good as the person giving it.