The Secret of Chimneys by Agatha Christie

In 1930, we get this dedication for the murder at the vicarage to Rosalind. The dedication here reads, To the Memory of My Best and Trueest Friend, My Mother. And that's extremely touching, especially since we know that Agatha Christie's mother had passed away by then. Also in the same year, we get our first double dedication. This would be for Giant's Bread by Mary West macad. It is one of my very favorite titles.