Other editions of book Lincoln, the unknown

From the foreword by Dale Carnegie: I went over to the British Museum library and read a number Lincoln books; and the more I read, the more fascinated I became. Finally I caught on fire and I was determined to write a book about Lincoln myself. I know that I had not the urge, temperament, training or ability necessary to produce a learned treatise for the benefit of scholars and historians. However, after reading many Lincoln volumes, I did think there was a genuine need for a short biography that would tell the most interesting facts about his career briefly and tersely for the average busy and hurried citizen of today. I have tried to write such a book