Willis, S. L. (1990). Maintaining professional competence: Approaches to career enhancement, vitality, and success throughout a work life. Jossey-Bass Publishers.
Citazione stile Chigago Style (17a edizione)Willis, Sherry L. Maintaining Professional Competence: Approaches to Career Enhancement, Vitality, and Success Throughout a Work Life. San Francisco: Jossey-Bass Publishers, 1990.
Citatione MLA (9a ed.)Willis, Sherry L. Maintaining Professional Competence: Approaches to Career Enhancement, Vitality, and Success Throughout a Work Life. Jossey-Bass Publishers, 1990.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.