Add DOIs to citations for common methods.

[ChrisKeefe]

replay citations deduplicates based on DOI, and citations without DOIs sometimes show up with annoying frequency.
Where possible, we can just add DOIs to citations.
After that, if things are still gross, we can make deduplication more robust.

[ChrisKeefe]

Closing. After cutting one PR based on this idea, I made deduplication more robust in #64