Gardner (1987, 1989) http://www.parentalalienation.com.au/maliciousmother.html

Malicious Mother Syndrome | Parental Alienation is Child Abuse

A notable exception can be found in the clinical writings of Gardner (1987, 1989)
who has ... In the typical case of Parental AlienationSyndrome, both mother and
child ... One woman refused to stop attacking her ex-husband through the courts ...

http://www.parentalalienation.com.au/maliciousmother.html