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The emergence of N.N. Luzin's research "Integral and a trigonometrical row" became an important event in the history of science. For the first time this work was published in 1915, and a year later it was presented to the physical and mathematical council of the Moscow University as the master thesis. In the council N.N. Luzin was awarded doctor's degree for this research at once. This event was preceded by the difficult period in the scientist's life. From the archival sources it has been found out that N.N. Luzin studied quite successfully at the university. Before the defence of the master thesis N.N. Luzin was on a scientific business trip in France and Germany twice where he communicated with famous European mathematicians. In the article new facts are provided which define the value of the Moscow professor D.F. Egorov in N.N. Luzin's fate. D.F. Egorov helped N.N. Luzin to enter the circle of scientific problems of that time, gave positive responses twice for N.N. Luzin's work "Integral and a trigonometrical row". The way which was done by N.N. Luzin in science, is instructive, and his thesis remains a model of the scientific creativity on mathematics so far.
