 Other professionals associated with a supportive model include Dr. Norman Spack of Children's Hospital Boston, Catherine Tuerk, MA, RN, Herbert Schreier, MD (Children's Hospital Oakland), and Ellen C. Perrin, MD of the Center for Children with Special Needs (CCSN) at TUFTS.Rosenburg (2002) recommends a parent-centered approach that helps parents learn to accept and support their child's identity and help the child to work through the issues surrounding identity, without trying to eliminate gender-variant behaviors.Other professionals, typified by Dr. Kenneth Zucker, the Head of the Gender Identity Service, Child, Youth, and Family Program and Psychologist-in-Chief at the Centre for Addiction and Mental Health in Toronto, believe in behavior modification to minimize childhood gender dysphoria.