I don't usually re-post cards, but I'm doing it this time, because I have new information and because this simple card was the most heartbreaking one I have ever encountered.
For a long time, this card was one of the most amusing ones I had ever encountered because of the message:
Dear Brother -  Wishing you a Happy Birthday and many more to come. Your sister (Hazel Vera)
(Wish I could see you just one minute. Maybe I wouldn't blister you.)
On  a lark, I decided to search the name of Rexford E. Holbrook. I don't do  this very often, because before you know it you're researching other  people's genealogy and there's no end.  Interestingly enough, I found  Hazel Vera before I found Rexford. Hazel was born in June, 1901, so she  was 14 when she sent this card to her 7 year-old brother who was visiting a relative in a nearby town.  But what's so  very tragic is that Hazel Vera died on September 28, 1915, only a month  after writing this.
Rexford  lived longer. I don't know when he died, but he did get married. He and  Hazel are both buried in the North Volney Cemetery in Oswego County, New  York. Here's the information posted on 
rootsweb:
HOLBROOK, HAZEL V.   lot 34 
1901   1915 
Born:  June 3, 1901  Palermo, NY 
Died:  September 28, 1915 
Father:  Ephraim L. Holbrook 
Mother:  Bertha Curtis 
(Vital Records Fulton)
The mystery was solved when Chris Overstreet responded with this information:
I found that Hazel had just taken the Regents (New York's high school  entrance exam) about a week before this postcard; then I found this:
Oswego 
Daily Times, Monday Evening, October 4, 1915
Hazel,  14 years old daughter of Mr. and Mrs. Ephraim Holbrook, died (last)  Tuesday at two p.m. at Lee Memorial Hospital, Fulton, where she was  operated upon the night previous for appendicitis. She had been ill  about a week. A consultation of doctors was held Monday and she was  taken to the hospital and operated upon. Besides her parents, she leaves  a sister, Mrs. Herman Hollenbeck of Clifford, and a little brother  Rexford.
Hazel was a member of the North Volney Sunday school and  was baptised at the church here by Rev. Mr. Williams a year and one day  previous to her death. She was also an attendant of the North Volney  school.
The funeral services were held at the family home in  Palermo Friday, October 1, at 2 p.m., Rev. Mr. Williams of Mt. Pleasant  officiating. Burial was made in North Volney cemetery. Much sympathy is  felt and expressed especially for Mrs. Holbrook who has lost her mother,  her sister, and now this daughter, all in about six months.
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Sepia Saturday.