Difference between refracting type telescope and reflecting type telescope
Refractors Vs Reflectors: The Pros & Cons of Each Telescope Design
Refractor vs. Reflector Telescopes: What's the Difference? | OPT Telescopes
How Telescopes Work Allison Hutton. History foundation for invention of the telescope was developed between 1350 and 1450 in 1570 the first actually instrument. - ppt download
Refractor vs reflector telescope: which is better? - BBC Sky at Night Magazine