SD and Micro SD card pins with description and functions
Micro SD card connector - PJS series - Yamaichi Electronics - locking / spring / board
Secure Digital (SD) card pinout diagram @ pinoutguide.com
Interfacing Microcontrollers with SD Card - openlabpro.com
MicroSD Pinout: A Step-by-step Guide
Matt Mets on Twitter: "ESP32 trick: Use your microSD jack as a JTAG connector! The ESP32 JTAG pins are all shared with the SDMMC bus, so you can use a microSD breakout