The lack of denominational infrastructure leaves a vacuum for inter-congregational discourse among Churches of Christ, one that often has been filled by publications and extra-church institutions such as colleges. These organizations, though overseen and run by members of Churches of Christ, were usually considered the work of individual Christians separate from the churches themselves. Among "brotherhood papers" in the mid-twentieth century, the "Gospel Advocate" and "Firm Foundation" were the oldest and most influential. Among colleges, the largest were Abilene Christian College, Pepperdine, Freed-Hardeman College, David Lipscomb College, and Harding College.