  If we want to assess whether the paper in question has had a particularly
high or low citation impact compared to other papers, the standard practice in
bibliometrics is to normalize citations in respect of the subject category and
publication year. A number of proposals for an improved procedure in the
normalization of citation impact have been put forward in recent years. Against
the background of these proposals this study describes an ideal solution for
the normalization of citation impact: in a first step, the reference set for
the publication in question is collated by means of a classification scheme,
where every publication is associated with a single principal research field or
subfield entry (e. g. via Chemical Abstracts sections) and a publication year.
In a second step, percentiles of citation counts are calculated for this set
and used to assign the normalized citation impact score to the publications
(and also to the publication in question).
