Hello, I am new to brewing, and have two extract batches under my belt. I would like to learn more about the math involved in the recipes that I often look at. I haven't messed with a hydrometer at all yet, so I haven't really cared up until now. Are there any useful books to look into are online resources to reference? I have messed with some of the online recipe calculators but right now I am just trying to familiarize myself with all of the variables to consider. Also if there is something out there that would explain all of the terms used in these calculators, that would be great. Thanks in advance.