please read wp rs some day and you will save us allot of trouble reliable sources are credible published materials with a reliable publication process their authors are generally regarded as trustworthy or authoritative in relation to the subject at hand wp rs so in other words these general opinion pieces on the subject of islamic contribution may by be reliable if cited as opinion in relation to say alhazen's history and his work on optics but these are not authoritative fact checked and scrutinized sources that specifically deal with the history of the telescope 'the subject at hand'