October 13, 1961

Or. Hilary Koprowski

The Wistar Institute
Thirty-Sixth Street at Spruce
Philadelphia 4, Pennsylvania
Dear Hilary:

Delighted!

Looking forward to sealng you here In December ~ at least this
time you can probably count on not being snowbound on your way to the
airport! Do you bring Irena with you?

Please remember me to Christopher.

Yours sincerely,

Joshua Lederberg
Professor of Genetics