R. Moshe Feinstein on the Necessary Level of Kashrut Supervision (30 Adar Rishon)
שו"ת אגרות משה יורה דעה ד:א 30 Adar 1, 5744 (1984)
How closely do we have to supervise factories that produce food? Do different foods need different levels of supervision? What makes for a good mashgiach (supervisor)?