Here is the direct and official download URL for the source tarball ( .tar.gz ):
curl -O https://imagemagick.org/archive/ImageMagick-7.1.1-15.tar.gz imagemagick 7.1.1-15 tar.gz download releases url
wget https://imagemagick.org/archive/ImageMagick-7.1.1-15.tar.gz or Here is the direct and official download URL