The paper is dedicated to one of the aspects of the problem of the explanation in history, i.e. to an analysis of the contribution of references of names of historical persons, places, events etc. into an explanation in history. An important condition of explanation is the relevancy of what explains to what is explained. The latter is determined by the correspondence of an explanation to the question it answers or the issue it is devoted to. Historical explanations usually employs historical names which are like proper names in many ways. As a result, relevancy of historical explanation depends on the coreferentialilty of those names with analogous terms used (in relevant ways) in formulations of what is explained. Two most popular theories of references of proper names are considered in the paper - the descriptive and the historical - and the conclusion is made that the complete coreferentiality of the desired type is unavailable in normal cases. Therefore the complete fulfillment of the condition of relevancy is also impossible for normal historical explanations.