I can find no references for 'Anja'. But I wonder if there may have been two roses named 'Anja' There appears to have been a pink shrub bred by Ewald Scholle in 1976. And then there is an orange pink floribunda introduced by Kordes in 1993.
I received this rose from the Europarosarium in Sangerhausen. The label is "Pimpinellifoliahybride Scholle" and so I asked Ewald Scholle about this rose and he told me that it is called "Anja" and was introduced by Kordes.