1937/08/28 Harvard Herald, Mrs. Frank Young Dies After Two Days' Illness in Muskogee, Oklahoma:
"Mrs. Frank W. Young, former resident of this city, passed away early yesterday morning, Aug. 25, at the family home in Muskogee, Okla., following an illness of only two days, according to a message received by Mrs. W. D. Hall, sister-in-law of Mrs. Young. Surviving besides the husband is one daughter, Mrs. Madelon Lawrason, and two granddaughters. Tentative arrangements made contemplate arrival of the body of the decedent and members of the funeral party in Harvard Friday evening, Aug 27, on the 5:30 passenger train. Burial will follow the same evening in Mount Auburn cemetery beside kindred dead."
© Northwest Herald, used with permission

Burbank mailed a postcard "Ute Indian Papoose" "to the Harvard Public Library (now Harvard-Diggins) on Aug 28, 1937

Now we know why Burbank mailed the postcard - he was unable to attend his sisters funeral, but wanted the people of Harvard to know he was thinking of her - his "baby sister".