"There exist other books explaining these concepts, but most of them were written according to scientific theories of earlier generations. With the advent of modern science, there have arisen many doubts and questions. Even those books that were written in our own generation are generally written so concisely that it is difficult to completely understand them. The above mentioned author explains all of this in agreement with modern scientific theory, fully and clearly enough that anyone can learn it and understand these concepts without doubts or questions."
by Rabbi Nathan Bushwick