These are two fun little spiralbound recipe booklets from the Colorado Interstate Gas Company. No exact date is given but by tracing the career of one of the Executive Chefs, Maurice Zeck, you can figure when he left Colorado for New Mexico and thus know the age of these books :).....the late 80s/very early 90s. They were created for cooking demos at Colorado Homebuilder"s Association Parade of Homes in Colorado Springs and are filled with great recipes from professional chefs around that city. The first one has 39 pages and Volume 2 has only 18 pages. But the food sounds terrific!