Darril Gibson is an IT author and the voice behind the website and blog Get Certified Get Ahead. He has published several books and training kits related to the A+ 800 exam series (220-801 and 220-802), the Network+ exams (N10-005 and N10-006) and the Security+ exam (SY0-401). Amazon has all the books and guides for sale. Many are also available in the Kindle format.

His Security+ Study Guide on Amazon is highly rated and a great value. We also recommend following Darril on Twitter. He ofter Tweets practice questions related to the A+, Network+ or Security+ exams. You can follow him here: https://twitter.com/DarrilGibson.