As one of three girls, who teaches with many girls who are also one of three girls in their family it seems important to celebrate a day such as this. There are many picture books about siblings, many of which focus on rivalry, but only a few of them are about sisters and what a good relationship they can have. The books listed here highlight many of the positive attributes having sisters can bring.
• Emma Dilemma Big Sister Poems by Kristine O'Connell George & Nancy Carpenter
• Big Sister Little Sister by LeUyen Pham
• Big Sister and Little Sister by Charlotte Zolotow & Martha Alexander
• Big Sister Little Sister by Gillian Shields & Georgie Birkett
• Seven Chinese Sisters by Kathy Tucker & Grace Lim
And of course, if you can't find these or you have older children there is always Michael Buckley's Sister's Grimm series.