First Telescope for Kids & Beginners, Portable Refractor Telescope with Tripod and 3 Eyepieces 20X 30X 40X- Best Gift for Kids to Explore Moon Space, View Wildlife, Watch Night-Sky - Walmart.com
World's sharpest' 250mm lens now on Kickstarter with swappable lens mount: Digital Photography Review
APO250VT F/8.8
Understanding the limits of your telescope - BBC Sky at Night Magazine
TEC 250mm APO - Refractors - Cloudy Nights
Three important equations to know for understanding telescopes | by Milky-Way.Kiwi | Why bother with Space | Medium