Building upon the bag of words approach, another tactic is to use a subset of terms as features [Moldovan et al. 2003], which can address issues related to article scaling while still encompassing the important concepts of an article [Tolle and Chen 2000]. One such method using this approach is noun phrasing. Noun phrasing is accomplished through the use of a syntax where parts of speech (i.e., nouns) are identified through the aid of a lexicon and aggregated using syntactic rules on the surrounding parts of speech, forming noun phrases.