"In the case of the conferences to which my husband went, they were international conferences and had the effect of widening the area where his books are sold and of very much increasing the sales of his own books and of books in which he has taken part and from which he derives income (the book entitled The Bomb: a Challenge is a case in point). They also greatly increased the demand among journalists and publishers for writings by him and interviews with him for publication, thereby contributing to his income."