diff --git a/pdf/2021-How_Gamification_Affects_Software_Developers_Cautionary_Evidence_from_a_Natural_Experiment_on_GitHub.pdf b/pdf/2021-How_Gamification_Affects_Software_Developers_Cautionary_Evidence_from_a_Natural_Experiment_on_GitHub.pdf new file mode 100644 index 00000000..942b1919 Binary files /dev/null and b/pdf/2021-How_Gamification_Affects_Software_Developers_Cautionary_Evidence_from_a_Natural_Experiment_on_GitHub.pdf differ