ABSTRACT
Professor Gustav Magnel (Belgium), in his lecture in the United States on 5 February 1954, presented his opinion, which this author feels is relevant even today:
As usual, when nobody knows anything concerning the problem, everybody formshis own theory andwrites a bookon this problem. Andwhen the problem is understood, then it is no longer necessary to write books, but only to take two pages of the writing paper, sufficient to solve such a problem without difficulties.
