Here are three excellent reviews which will help with the diagnosis and management of patients with chronic itching.
1. Somatic and Psychiatric considerations: Download Chronic Pruritus
2. Guidelines on Chronic Pruritus from the European Dermatology Forum: Download Guideline-on-Chronic-Pruritus
3. Clinical Classification of Itch: a Position Paper Download Clinical Classification of Itch
These are very helpful articles for physicians and lay persons with itch-related disorders.