Citation Hunt

The Wikipedia snippet below is not backed by a reliable source. Can you find one?

Click I got this! to go to Wikipedia and fix the snippet, or Next! to see another one. Good luck!

In page Phenylketonuria:

"

Phenylketonuria was discovered by the Norwegian physician Ivar Asbjørn Følling in 1934[3] when he noticed hyperphenylalaninemia (HPA) was associated with intellectual disability. In Norway, this disorder is known as Følling's disease, named after its discoverer.[4] Følling was one of the first physicians to apply detailed chemical analysis to the study of disease.[citation needed]