The text you're looking for likely refers to the The Art of Boudoir Photography with Speedlights
Off-Camera Triggers: Mounting your flash on your camera’s "hot shoe" often results in flat, unflattering light. Use a wireless transmitter and receiver to move the light off-camera and create depth. the art of boudoir photography with speedlights pdf.zip
The ebook covers several critical areas to help you master the art of boudoir: The text you're looking for likely refers to
To get the most out of your speedlights, you’ll need a few essentials beyond the flash itself: the art of boudoir photography with speedlights pdf.zip