|Other Retailer||Price Checked Time||Their Price in AUD||Our Price|
|Amazon UK||4 days ago||35.62||$21.30||You save $14.32|
|Amazon US||5 days ago||26.55||$21.30||You save $5.25|
|Book Depository US||today||21.73||$21.30||You save $0.43|
Norman Sperling has has been an assistant editor at "Sky & Telescope" magazine and served as the Science Editor of AltaVista.com. He co-designed Edmund Scientific's Astroscan telescope and wrote "What Your Astronomy Textbook Won't Tell You." He edits "The Journal of Irreproducible Results" (www.jir.com) and teaches astronomy in universities around San Francisco, CA.