Using old Mini PCIE WLAN cards in modern laptops – Gsid works
EC20 Mini PCIe Hardware Design
Can a PCIe X1 fit in a mini PCIe (WiFi card) slot? - Quora
Amazon.com: Ableconn MPEX-M2WL Mini PCIe Adapter with M.2 Key E Slot - Support PCIe and USB Based M.2 E Key and A-E Key Module for Mini PCI Express - Work for WiFi
PCI card pinout - YouTube
Amazon.com: Mini Pcie USB Adapter SIM to USB Adapter with SIM Card Slot for WWAN/LTE Module : Electronics
RAK8213 mini PCIe Card Comes with GNSS, NB-IoT & eMTC Connectivity - CNX Software