| http://www.w3.org/ns/prov#value | - of the formulae ##STR15## in which R.sub.4 is hydrogen or a C.sub.1 -C.sub.6 alkyl group, R.sub.9 is as defined above, in particular hydrogen or methyl, R.sub.10 and R.sub.11, independently of one another, are hydrogen or a linear or branched C.sub.1
|
