Ace on the River by Barry Greenstein Not everyone wants to read a strategy guide or get deep into the math of poker, so let’s take a break from the textbooks and find out more about other areas of the pgslot game, with Barry Greenstein’s Ace on the River. This book is a fresh look at the game of poker through the eyes of a professional player. Players can learn a lot by reliving Greenstein’s experiences as he worked and played his way to becoming one of the greats.