The Concept of Anxiety
All of Kierkegaard's books have either a preface, dedication, or prayer at the beginning. This book includes a lengthy introduction. "The Concept of Anxiety" was published on exactly the same date as "Prefaces", June 17, 1844. Both books deal with Hegel’s idea of mediation. Mediation is a common thread throughout Kierkegaard’s works. His work up to this point was to show that faith was being mediated by knowledge. Here he takes up the questions of sin and guilt.
David H. Barlow
As Barlow's ideas of the nature and origins of anxiety started to become more elaborate, he published a series of books that delineated the results from his research and advocated for a more empirical scientific approach to clinical psychology. In 1985, he published the first edition of the "Clinical handbook of psychological disorders: A step-by-step treatment manual", explicating evidence based practices. Aggregating his ideas from this period of extensive research, Barlow published what the "American Psychologist" deemed as his "most influential book", "Anxiety and its disorders: The nature and treatment of anxiety and panic".