I've been in the same situation multiple times. I don't recall a case where the data was of critical importance, so I could get away with it, but using the part

I've been in the same situation multiple times. I don't recall a case where the data was of critical importance, so I could get away with it, but using the parts of the passphrase I knew in a combined bruteforce/dictionary attack definitely crossed my mind. Do you have some links to reference material on how to achieve that?