epub_book: The EPUB e-book format
In rameshbalan/write_book: Authoring Books and Technical Documents with R Markdown

Convert a book to the EPUB format, which is is an e-book format supported by many readers, such as Amazon Kindle Fire and iBooks on Apple devices.

epub_book(fig_width = 5, fig_height = 4, dev = "png", fig_caption = TRUE, 
    number_sections = TRUE, toc = FALSE, toc_depth = 3, stylesheet = NULL, 
    cover_image = NULL, metadata = NULL, chapter_level = 1, epub_version = c("epub3", 
        "epub"), md_extensions = NULL, pandoc_args = NULL, template = "default")

`fig_width, fig_height, dev, fig_caption`	Figure options (width, height, the graphical device, and whether to render figure captions).
`number_sections`	Whether to number sections.
`toc, toc_depth`	Whether to generate a table of contents, and its depth.
`stylesheet`	A character vector of paths to CSS stylesheets to be applied to the eBook.
`cover_image`	The path to a cover image.
`metadata`	The path to the EPUB metadata file.
`chapter_level`	The level by which the e-book is split into separate “chapter” files.
`epub_version`	Whether to use version 3 or 2 of EPUB.
`md_extensions`	A character string of Pandoc Markdown extensions.
`pandoc_args`	A vector of additional Pandoc arguments.
`template`	Pandoc template to use for rendering. Pass `"default"` to use Pandoc's built-in template; pass a path to use a custom template. The default pandoc template should be sufficient for most use cases. In case you want to develop a custom template, we highly recommend to start from the default EPUB templates at https://github.com/jgm/pandoc-templates/.