Ferri's Differential Diagnosis: A Practical Guide to the Differential Diagnosis of Symptoms, Signs, & Clinical Disorders, second edition This is a portable, concise guide to differential diagnosis for over 900 signs, symptoms & clinical disorders. Differential diagnoses are listed both by presenting sign or symptom & by clinical disorder, so you can confirm your diagnosis accurately, completely, & quickly. This is a versatile, easy-to-use reference you'll consult every day.