For parents, coaches, and physicians responsible for protecting youngsters who play sport there are a number of excellent resources available.
The clearest and best concussion guideline, I believe, is The Consensus Statement on Concussion in Sport: the 3rd International Conference on Concussion in Sport held in Zurich, November 2008 published in Br J Sports Med 2009;43(Suppl I):i76–i84. doi:10.1136/bjsm.2009.058248. The Consensus Statement is available at http://bjsm.bmj.com/content/43/Suppl_1/i76.full.pdf.
This is an update created on 6-23-2017
Here are a list of resources from Parachute Canada:
Concussions are considered the “invisible” injury, since they do not show up on medical imaging tests such as x-rays or CT scans. But they are also considered “invisible” because their effects are often misunderstood. The following resources are designed to help physicians, nurses, students and other healthcare professionals understand and navigate the sometimes difficult process of recovery from concussion.
Further resources are available at http://preventingconcussions.org/index.php/resources
The acute concussion evaluation (ACE) form for the office physician is available at http://preventingconcussions.org/index.php/assessments_tools. It is good but the four page SCAT2 form is better to me.
The Standardized Assessment Concussion Tool 2 has excellent concise guidance on return to activity as well as an assessment template. It and the Consensus Statement above are the resources you need to have on your computer or tablet. And the authors have graciously made them freely available without copyright restrictions.