def filter_by_book_style(bibtexs, book_style):
    """Returns bibtex objects of the selected book type.

    Args:
        bibtexs (list of core.models.Bibtex): queryset of Bibtex.
        book_style (str): book style key (e.g. JOUNRAL)

    Returns:
        list of Bibtex objectsxs

    """
    return [bib for bib in bibtexs if bib.bib_type_key == book_style]