_output.yml

bookdown::gitbook:
  css: style.css
  includes:
       in_header: GA_Script.html
  config:
    toc:
      collapse: section
      before: |
        <li><a href="./">Introduction to Regression</a></li>
      after: |
        <li><a href="https://github.com/rstudio/bookdown" target="blank">Published with bookdown</a></li>
    edit: https://github.com/rstudio/bookdown-demo/edit/master/%s
    download: ["pdf", "epub"]
bookdown::pdf_book:
  includes:
    in_header: preamble.tex
  latex_engine: xelatex
  citation_package: natbib
  keep_tex: yes
bookdown::epub_book: default