(Sarcasm.)
“Dalyos Yechezkel” vol. 4, pages 432-435 has something called: דברים נבחרים מכתבי מוה”ר נתן ז”ל.
He means Rabbi Nosson Sternhartz, the main student of Rabbi Nachman of Breslov.
(The contents are often either incorrect or too brief to be useful.)
It’s so short it’s likely just “שלא להשאיר הגליון חלק”. And it’s missing from the Table of Contents, too (איידי דזוטר מירכס maybe?).
But still…!
On the other hand, Rabbi Sarna, a student of the Alter, was sure a Litvak in other ways…