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Prints the first or last entries of a BibEntry object (via message) and returns them invisibly (via invisible).


# S3 method for BibEntry
head(x, n = 6L, suppress.messages = TRUE, ...)

# S3 method for BibEntry
tail(x, n = 6L, suppress.messages = TRUE, ...)



an object of class BibEntry.


a single integer. If positive, size for the resulting object: number of elements for a vector (including lists), rows for a matrix or data frame or lines for a function. If negative, all but the n last/first number of elements of x.


boolean; should the head/tail entries be printed via message?


arguments to be passed to or from other methods.


an object of class BibEntry.


If suppress.messages is FALSE, the head/tail entries are output to the console along with some additional formatting for the ‘bibtype’ and ‘key’, in addition to invisibly returning the entries.


if (requireNamespace("bibtex")) {
    file <- system.file("Bib", "biblatexExamples.bib", package = "RefManageR")
    BibOptions(check.entries = FALSE)
    bib <- ReadBib(file)
    tail(bib, 2, suppress.messages = FALSE)
    bib <- head(bib, 1, suppress.messages = TRUE)
#> [[91]] Thesis: geer
#> [1] I. de Geer. “Earl, Saint, Bishop, Skald~- and Music. The Orkney
#> Earldom of the Twelfth Century. A Musicological Study”. PhD thesis.
#> Uppsala: Uppsala Universitet, 1985.
#> [[92]] Thesis: loh
#> [1] N. C. Loh. “High-Resolution Micromachined Interferometric
#> Accelerometer”. MA Thesis. Cambridge, Mass.: Massachusetts Institute of
#> Technology, 1992.