However he resigned in 1918 , because he did not like the administrative burden .
He was a good friend of Oskar Backlund , and when the latter died in 1916 , he succeeded him as director of Pulkovo Observatory .
Friend resigned in 1918 , because friend did not like the administrative burden .
He was a good friend of Oskar Backlund , and when the latter died in 1916 , he succeeded him as director of Pulkovo Observatory .