I suspect most of your viewers who collect early incandescent lamps already know this, but in case some don't know, here goes. Collecting early books on the subject can be expensive as well as difficult. However, we now live in a time when one's purse need not be affected. In my opinion one of the desirable early lamp history books is that by E. Alglave and J. Boulard, titled The Electric Light: Its History, Production and Application. Today you can "have" this book by typing "Alglave and Boulard" in Google, the search engine. The first listing is that book, all 458 pages. Enjoy!