Engstrom, T. W. (1985). The fine art of friendship: Building and maintaining quality relationships. Thomas Nelson.
Lua i Stíl Chicago (17ú heag.)Engstrom, Ted W. The Fine Art of Friendship: Building and Maintaining Quality Relationships. Nashville: Thomas Nelson, 1985.
Lua MLA (9ú heag.)Engstrom, Ted W. The Fine Art of Friendship: Building and Maintaining Quality Relationships. Thomas Nelson, 1985.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.