APA citation style - 7th edition
Patents
Note: The URL is optional, however, it should be included if it is available.
Erb, R., Warmouth, C., Long, V. R., & VanHoutin, L. A. (2018). Football helmet shell. U.S. Patent and Trademark Office. https://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=D836253.PN.&OS=PN/D836253&RS=PN/D836253
Note: The in-text citation for the above patent would be:
(Erb et al., 2018)