The second book in the Hourglass Door trilogy. Dante was unlike anyone Abby had ever met. Now he's gone, and Abby will do anything to get him back . . .

Dante, a prisoner sent from fifteenth-century Italy into the present time as punishment, meets and falls in love with Abby, a high school senior who may be the

The elegance of mathematics meets the creativity of art in this unique coloring book. The golden ratio is the mathematical equation that describes what many con

In this invaluable book, the basic mathematical properties of the golden ratio and its occurrence in the dimensions of two- and three-dimensional figures with f

First published in 1202, Fibonacci’s Liber Abaci was one of the most important books on mathematics in the Middle Ages, introducing Arabic numerals and method