Doing Research
H. T. Kung wrote in 1987, while at CMU, a text on Ph.D. Advice which still has relevant information for potential PhD students and makes an interesting reading about research activities.
Richard Hamming (as in Hamming distance or Hamming code) often delivered a speech with the title “You and Your Research”. You can read the transcript of one of them or find videos on YouTube; in either form, it is worth it.