1. N. Burshtein, Oral communication to P. Erdös, Nice, September 1970.
2. On distinct unit fractions whose sum equals 1;Burshtein;Discrete Math.,1973
3. N. Burshtein, On distinct odd integers the sum of whose reciprocals equals 1, to be submitted.
4. On the solutions in integers of a/b=x1-1+⋯+xn-1;Erdös;Mat. Lapok,1950
5. On a problem concerning congruence systems;Erdös;Mat. Lapok,1952