Review of Developments
Francis G. Cornell · Review of Educational Research · 1950
CONTRIBUTORS to this REVIEW have observed, as have authors of earlier numbers, that not only is it difficult to locate literature which is strictly acceptable in terms of research criteria but it is also extremely difficult to exclude material which does not meet these same criteria. This committee has found it necessary to include the latter type items either because these writings provide the only sources of significance dealing with the problem under review or because of an unusual line of reasoning on the subject, in most cases from an authoritative source. These we may call marginal references in the field. It is unfortunate that research properly defined is so limited in this area that it is necessary to depend upon many of these marginal sources.