Extract all the authors named in this paragraph on the controversies about Nobel laureate selections

- Leo Tolstoy
- Henrik Ibsen
- Émile Zola
- Mark Twain
- Sully Prudhomme
- Rudolf Eucken
- Algernon Swinburne
- Selma Lagerlöf
- Romain Rolland
- Erik Axel Karlfeldt
- Verner von Heidenstam
- Pearl Buck
- John Steinbeck
- Jean-Paul Sartre
- Aleksandr Solzhenitsyn
- Graham Greene
- Vladimir Nabokov
- Saul Bellow
- Eyvind Johnson
- Harry Martinson