No idea about any resources, I just interact with elementals and nymphs normally like any spirits. Wind elementals and nymphs are a favourite since they control the weather and they're fun and cheerful. They're also very responsive if you ask nicely and treat them right. For example getting rain is just a sigil away if you want.
Fire elementals: a bit harder to handle, they don't control themselves once the fire starts, so if you have wildfires going you're not going to be able to change that by talking to them, they enter a fiery trance state and can't be effected until everything was burned.
There are more elements and elementals than just the 4 or 5, if you expand your view you can find and connect with spirits maintaining different aspects of human life. They can all be bargained with, if you treat them right. They're also potentially very destructive and careless, even if they're nice talking to, so keep in mind they do not really care about humans even if they seem very "humane."