Are both these usages correct, and if so is one preferred?
... and was further established in follow-up studies (e.g., Doe et al., 2013).
... and was further established by follow-up studies (e.g., Doe et al., 2013).
The intent is that the follow-up studies helped to confirm/establish the original premise. I am uncertain if "in" or "by" is more appropriate. I personally think both are fine, but I am far from an expert in English and may be overlooking an important nuance.