Mettling, Stephen: - Stephen Mettling and David Cusic have operated one of the nation's most successful custom training organizations specializing in real estate program development. They are perhaps best known for writing Principles of Real Estate Practice, a national real estate principles textbook used by over 50,000 students per year. Stephen Mettling has been a real estate educator and custom training program developer specializing in real estate over the past forty years. During that time he has written or co-developed over 100 books, professional training programs and texts covering all aspects of residential, commercial, and corporate real estate for national trade organizations and real estate companies. Additionally Steve has directed numerous statewide real estate schools and served as vice president of Dearborn Financial Services where he headed up the country's largest real estate, securities and insurance license training network.Dr. Cusic, an author and educator, has been engaged in vocation-oriented education since 1966. David earned his Ph.D in linguistics from Stanford University. Specializing in real estate training since 1978, he has developed numerous real estate training programs for corporate and institutional clients around the country including NAR, CoreNet Global, and the CCIM Institute.​Ryan Mettling, partner and currently publisher of Performance Programs, is an accomplished online curriculum designer, author and course developer.