University extension 81 Distance education 27 Correspondence schools and courses 13 Academic libraries 8 Adult education 8 Universities and colleges 7 Congresses 6 Library extension 6 History 4 Libraries and students 4 Education 3 Open learning 3 Continuing education 2 Curricula 2 Directories 2 Document delivery 2 Education, Higher 2 Independent study 2 Off campus services 2 Administration 1 Aims and objectives 1 Attitude 1 Case studies 1 College dropouts 1 College facilities 1 College teachers 1 College teaching 1 Colleges of advanced education 1 Comparative education 1 Evaluation 1