diff --git a/lectures/_config.yml b/lectures/_config.yml
index 4ef54425..d9e0aa26 100644
--- a/lectures/_config.yml
+++ b/lectures/_config.yml
@@ -33,6 +33,7 @@ latex:
 sphinx:
   extra_extensions: [sphinx_multitoc_numbering, sphinxext.rediraffe, sphinx_tojupyter, sphinx_exercise, sphinx_togglebutton]
   config:
+    bibtex_reference_style: author_year
     linkcheck_ignore: ['https://doi.org/10.3982/ECTA8070',
                        'https://doi.org/10.1086/261749',
                        'https://doi.org/10.1086/262078',
@@ -69,6 +70,7 @@ sphinx:
        ['latex', 'text/html', 70],
        # Link Checker
        ['linkcheck', 'text/plain', 10],
+       ['linkcheck', 'text/html', 20],
      ]
     html_favicon: _static/lectures-favicon.ico
     html_theme: quantecon_book_theme