| http://www.w3.org/ns/prov#value | - her, but the total (a+b+c) is equal to a whole or fractional number from 2 to 4; R is a hydrogen atom or an alkyl group having 1 to 4 C atoms; A is a direct bond or a group of the general formulae --(CH2)m -- or --(CH2)n --NH-- in which m is a whole number from 1 to 4 and n is a whole number from 2 to 6; B is the phenylene or naphthylene radical which can be substituted by substituents, preferably
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