\usepackage{hyperref}

"Another way is to use special field url and make bibliography style recognise it.

url = "http://www.example.com"

You need to use \usepackage{url} in the first case or \usepackage{hyperref} in the second case."

Source: https://en.wikibooks.org/wiki/LaTeX/Bibliography_Management#Authors

Paper.tex

@@ -1,6 +1,7 @@
 \documentclass[9pt,oneside]{amsart}
 %\usepackage{tweaklist}
 \usepackage{url}
+\usepackage{hyperref}
 \usepackage{cancel}
 \usepackage{xspace}
 \usepackage{graphicx}