Hi @Justme and welcome to the forum.
You’ve guessed correctly… this subject has been thrashed about quite a bit already…
If you click on the magnifying glass icon and type in your brief question (I just typed EES CdS) it comes up with threads incorporating the “typed words”… thus you can locate where we have discussed “whatever…”
Here is just one example…
There are many different Categories on the Forum… you might like to browse through the “Travel” Category… you’ve joined us on the “Ask Anything” category… 
which is fine to start with… but heading straight for the correct Category might be useful for you.