Hello,
I am wondering if anyone is aware of which papers MNE implements in its mne.preprocessing module? Particularly, I am interested in learning about the mne.preprocessing.find_ecg_events and mne.preprocessing.find_eog_events.
I have looked a the documentation and source code for both, and though I understand how each event is being calculated, I did not find an academic reference as to why it is being calculated that way.
The QRS detector used for heartbeat detection was initially added by @Denis and subsequently altered by @larsoner. Maybe they have some resources at hand they could share with you.
To me based on GitHub sleuthing it looks like it was added 10 years ago by someone named @agramfort 
I don’t know of any academic reference for it, but it looks like our first version was just looking for values that were some number of standard deviations above the mean.
If you need something citable, you may also consider simply finding ECG peaks and EOG activity using NeuroKit2; they seem to offer a wide variety of algorithms with references! And it interoperates with MNE, too
it’s just code that was used in house at MGH by Sheraz
Alex