- http://www.homedepot.com/b/Tools-Hardware-Hand-Tools-Hex-Keys/N-5yc1vZc265
- https://www.amazon.com/s/ref=sr_st_price-desc-rank?keywords=robertson+screwdriver&rh=n%3A228013%2Ck%3Arobertson+screwdriver&qid=1474854116&sort=price-desc-rank
- http://www.homedepot.com/p/Klein-Tools-Cushion-Grip-No-2-Square-Recess-Tip-Screwdriver-with-Round-Shank-662/202282844
- https://en.wikipedia.org/wiki/P._L._Robertson
- https://www.amazon.com/Stanley-66-039-Jewelers-Precision-Screwdriver/dp/B00002X29G
- https://www.amazon.com/s/ref=sr_st_price-desc-rank?keywords=jewelers+screwdriver+set&rh=n%3A228013%2Ck%3Ajewelers+screwdriver+set&qid=1474853948&sort=price-desc-rank
- https://www.amazon.com/TEKTON-2944-Offset-Screwdriver-3-Piece/dp/B000NY8OQU
- http://www.homedepot.com/p/Husky-8-in-1-Precision-Torx-Screwdriver-Set-70381H/204664390
- http://forums.macrumors.com/threads/advantage-of-torx-screwdrivers.497926/
- http://www.lowes.com/c/Tools
- http://www.acontinuouslean.com/2013/04/05/a-better-way-to-screw/
- http://www.howstuffcompares.com/doc/s/slotted-screwdriver-vs-philips-screwdriver.htm
- http://boards.straightdope.com/sdmb/showthread.php?t=80378