Books can be attributed to "Unknown" when the author or editor (as applicable) is not known and cannot be discovered. If at all possible, list at least one actual author or editor for a book instead of using "Unknown".
Books whose authorship is purposefully withheld should be attributed instead to Anonymous.
Psychotherapist Dr Judith Edwards has chosen to discuss Narrative of a The Psychoanalytic Treatment of Children by Anna Freud on FiveBooks as one of the top five on her subject - Child Psychotherapy, saying that:
"...Anna Freud’s work centred more on the school-age child. The interpretation of the raging id, that seething cauldron full of unacceptable and uncivilised urges, was, she thought, ‘only a means to an end’ and she saw the ego as ‘the proper field of observations. It is, so to speak, the medium through which we try to get a picture of the two other institutions’. She was much more open to the notion of the power of environmental influences, and the primary significance of the parents...."