sentences:  Levenkron started his research in 1970 and later took part in the National Association of Anorexia Nervosa and Associated Disorders.He gained popularity due to his 1978 novel "The Best Little Girl in the World", which was recognized as a Best Books for Young Adults by the American Library Association and which later formed the basis of the American Broadcasting Company's television film "The Best Little Girl in the World".His notable clients included Karen Carpenter, who died in 1983.