Dear Dr. Pfeifer,
I feel very sad to hear the bad news so suddenly.
Your death is too early.
You gave so much to us and I learned a lot from you.
I would like to express my heartfelt gratitude to your strict, but warm hearted teaching.
You were truly a great man and I will miss you.
You will be in my heart forever.
My sincere condolences are extended to his family.