By the time Sonia obtained her PhD, she already had two single-author papers published in Communications in Mathematical Physics; the first paper containing a proof of a conjecture of Don Zagier stated in the preceding paper in the same issue of the journal.
Paper [8] was also accepted in Communications in Mathematical Physics, subject to a substantial reduction in size. By the time the referee got around to sending the report, we had already moved on and this revision never took place. (I wonder whether they would still publish the shortened version.)
Paper [25] was submitted to JHEP, but Sonia's illness prevented her from ever responding to the referee, with whose report she largely disagreed. After her death an editor suggested publishing the paper, but not before being modified either "by me or by someone of their choosing" in order to incorporate the wishes of the referee. I believe that a scientific publication is ultimately a form of self-expression and could not in good conscience either pretend to speak on Sonia's behalf or else allow anyone else to do so. The only option was therefore to withdraw the submission from the journal, a decision which was greeted by a condescending email from the editor in which I was lectured on the subject of peer review and on how Sonia's memory should be honoured. Na, ja...
Sonia had been working on the extension of the results of [25] to other Lie groups and had already written a substantial draft.
At last count, paper [20] has received 87 citations and paper [6] has received 70; whereas [19] and [23] have received 50 or more.