What is associated with: around 1920 plates of this silicon mineral were first used to control radio frequencies?

What is associated with: around 1914 the gulf oil company became the first to give away these free guides to travelers? What is associated with: around 1915 debussy composed 12 etudes in memory of this polish french composer? What is associated with: around 1915 this italian painted an elongated asymmetrical portrait of artist juan gris? What is associated with: around 1916 newspaper writer don marquis created this typing cockroach friend of mehitabel the… What is associated with: around 1927 this american known for his mobiles created a portrait of josephine baker out of w… What is associated with: around 1930 angelos sikelianos tried to revive the famous festival of this town navel of the w… What is associated with: around 1930 william lear invented one of these for the car marketed under tha name motorola? What is associated with: around 1940 scientists found that mutations in these chromosomal units result in defective enz…