This midnight, I tried to compile my $\rm \LaTeX$ document with a so-called “bibliography”, which contains a URL. The link should be in typewriter font after using the command \urlstyle{tt} under adding the url package to the preamble. I googled for almost 2 hours, but the blog posts suggested that using this method should work. I even tried to copy some minimum working examples from the web to test if they work. They really worked and so I’m puzzled. Ten minutes ago, I just find out what’s going wrong: the url package should never go before the several lines in the preamble that are responsible for adding an APA-style bibliography.

The \ll command in Vim-$\rm \LaTeX$ seems not doing well with Biber. Whenever the AUX file exists, \ll won’t execute biber, causing the resulting PDF file to have no change in the bibliography.

I hope I can use less time to figure out any mistake next time.