This could be a good start: https://books.google.com.my/books?id=-6L8g7EY9ZwC&pg=PA72&lpg=PA72&dq=psychoanalyst+sophie+morgenstern&source=bl&ots=Y7d2-DMsq_&sig=AXWzQKgO0uvXUkIWNiMFQReBKKE&hl=en&sa=X&ved=0ahUKEwjQh8nEmM_ZAhUG6bwKHW0kCykQ6AEIXDAN#v=onepage&q=psychoanalyst%20sophie%20morgenstern&f=false
You can go on the French National Library website, then you have a full access of the Revue Française de Psychanalyse : http://gallica.bnf.fr/ark:/12148/cb34349182w/date
Then you search for Sophie Morgenstern and you find several occurrences
For example: http://gallica.bnf.fr/ark:/12148/bpt6k1103926/f39.image.r=sophie%20morgenstern
I did not work directly on Morgenstern, but I can also send you some other stuff about her since she was connected to Marie Bonaparte (my PhD subject).
Merci beaucoup par votre aide! Je vais chercher ce link qui m'a envoyé, mais si vous pouvez m'envoyer un autre matériel, je serais très reconnaissant. Mais dans ce link il y a beaucoup de chose.