Who should I call to write a letter of recommendation to Cobb?

I suggest choosing someone who knows you well enough and appreciates you very much. (very important)

We don't care whether the recommender is familiar with himself or not, and whether he has completed a certain research or project together before, but it is not correct to ask the other party to write a letter of recommendation with high gold content for himself just for the title and reputation of the recommender.

We need to know what we have to do with referees, such as taking professional courses taught by referees, guiding your classroom work, and participating in some scientific research projects together to impress referees in class. It is much better to choose a teacher who takes you as a referee than a professor Daniel who doesn't know you very well. Moreover, we need to trouble our recommender more than once, for example, we need his detailed personal information, check the contents of the recommendation letter, sign, send and receive emails and so on. So it is a wise choice to find a teacher who has a good relationship with you as your reference.