Several. Here's one, Build Your Own AR15 that will sell you a step by step manual for $7. Cheap at twice the price IMHO. Although I used AR15.com and ShaneDaughtry.Com (real photos verses drawings) to assemble my lower. (Be sure to buy the pivot pin installation tool, it's cheap and makes the hardest step not the hardest at all). You'll also need the stock wrench or the multi wrench.
Thank you my friend. There’ll be a few more assembled for our side before too long.