1. Still, AT. Philosophy of osteopathy. Kirksville, MO: AT Still; 1899.
2. McConnell, CP. Osteopathic studies: soft tissue technic integration. J Am Osteopath Assoc 1932;31:297–301.
3. Cain, RA. Promoting osteopathic thought in clinical education, every patient, every day: a patient-centered, systems approach to health and illness: Proactive Health Management; 2011.
4. Seffinger, MA, editor. Foundations of osteopathic medicine, 4th ed. Philadelphia, PA: Wolters Kluwer; 2018.
5. Stiles, EG. Chapter 24: primary lesion, key lesion, sequencing. In: Mayer, J, Standen, C, editors. Textbook of osteopathic medicine: Elsevier; 2017:265–70 pp.