lib/iso_bib_item/iso_bibliographic_item.rb
def to_most_recent_reference
      me = DeepClone.clone(self)
      me.disable_id_attribute
      @relations << DocumentRelation.new(type: "instance", identifier: nil, url: nil, bibitem: me)
      @abstract = []
      @dates = []
      @docidentifier.each(&:remove_date)
    end
def to_most_recent_reference
      me = DeepClone.clone(self)
      me.disable_id_attribute
      @relations << DocumentRelation.new(type: "instance", identifier: nil, url: nil, bibitem: me)
      @abstract = []
      @dates = []
      @docidentifier.each(&:remove_date)
    end
convert ISO:yyyy reference to reference to most recent
 instance of reference, removing date-specific infomration:
 date of publication, abstracts. Make dated reference Instance relation
 of the redacated document