diff --git a/vignettes/the_theory.Rmd b/vignettes/the_theory.Rmd
index 38d15d9..ef72e65 100644
--- a/vignettes/the_theory.Rmd
+++ b/vignettes/the_theory.Rmd
@@ -191,7 +191,7 @@ print(model$final_r)
 ```
 
 For more details read
-[Ruby C. Weng and Chih-Jen Lin (2011)](http://jmlr.csail.mit.edu/papers/volume12/weng11a/weng11a.pdf)
+[Ruby C. Weng and Chih-Jen Lin (2011)](https://jmlr.csail.mit.edu/papers/volume12/weng11a/weng11a.pdf)
 
 ## Dynamic Bayesian Logit
 Following algorithm gives some advantages over mentioned rating systems, allowing