Shiurim in this topic
Volume 17, Letter #6419: The Rebbe responds to various questions related to mourning (אבלות) and also discusses the correct spelling of the name Mendel.
Volume 10, Letter #3113: In this letter, the Rebbe addresses דוד גרטנר, mentioning that there is a special obligation incumbent on those who have engaged in the sciences (מדעים).