Q. How do I create a reference list in APA style where some of the references start with numbers?

Alphabetize the entry in the reference list as though the number were spelled out. So a reference that begins with 50 would be alphabetized as though 50 were written fifty. More information is available at http://blog.apastyle.org/apastyle/2017/04/how-to-alphabetize-a-number.html