pkgVer <- function(pkg, default) { 
    x <- packageDescription(pkg, fields = 'Version')
    ver <- ifelse(is.na(x), default, x)
    paste0('https://github.com/lcolladotor/', pkg, ' - R package version ', ver)
}
c(
    bibentry(bibtype="manual",
        title = "derfinderHelper: derfinder helper package",
        author = personList(
            as.person("Leonardo Collado-Torres"),
            as.person("Andrew E. Jaffe"),
            as.person("Jeffrey T. Leek")
        ),
        year = 2014,
        url = "http://www.bioconductor.org/packages/release/bioc/html/derfinderHelper.html",
        note = pkgVer('derfinderHelper', '1.0.4')
    ),
    bibentry(bibtype="manual",
        title = "derfinder: Annotation-agnostic differential expression analysis of RNA-seq data at base-pair resolution",
        author = personList(
            as.person("Leonardo Collado-Torres"),
            as.person("Alyssa C. Frazee"),
            as.person("Andrew E. Jaffe"),
            as.person("Jeffrey T. Leek")
        ),
        year = 2014,
        url = "http://www.bioconductor.org/packages/release/bioc/html/derfinder.html",
        note = 'https://github.com/lcolladotor/derfinder - R package version 1.0.6'
    )
)
