doi2bib.r

#' Convert doi to bibtex
#'
#' Convert a digital object identifier (doi) string into a bibtex entry using the
#' webserice \link{http://www.doi2bib.org}.
#'
#' @param doi The character  string of the doi.
#'
#' @return a bibtex entry as a character string.
#'
#' @importFrom httr accept content GET
#'
#' @example
#' doi2bib("10.1038/350132215)
#'
#' @export

setGeneric(
  "doi2bib",
  function(doi) {
    standardGeneric("doi2bib")
  }
)

setMethod(
  "doi2bib",
  c(doi = "character"),
  function (doi) {
    content(
      GET(
        url    = "http://www.doi2bib.org/",
        config = accept("application/x-bibtex"),
        path   = "doi2bib",
        query  = list(id = doi)
      ),
      as = "text"
    )
  }
)

Ah, found your package. Google found this first, I'll leave this link here for others that might stumble here first like I did:
https://github.com/wkmor1/doi2bib