OWC 4GB (2x2GB) PC3-8500 DDR3 1066MHz SODIMM 204 Pin Memory Upgrade Kit for Late 2008, Early 2009/2010 MacBook, MacBook Pro Unibody, Mac mini, 2009 iMac, Late 2009 MacBook 13" . Model OWC8566DDR3S4GP - Newegg.com
OWC 8GB RAM Kit (2x4GB) iMac Early 2009 - Late 2009 - 4mac
Install memory in an iMac - Apple Support
Install memory in an iMac - Apple Support
iMac Early 2009 (20-inch and 24-inch) RAM Upgrade Dallas – Apple Mac Computer Repair Dallas , Laptop ,Desktop ,iMac ,MacBook iPhone iPad Data Recovery ,Virus
How to Upgrade Intel Mac mini RAM (Polycarbonate): EveryMac.com
With a few inexpensive upgrades (ram and SSD), this early 2009 mac mini runs Mojave surprisingly well : r/mac