Knock! Knock! Who's there? It's Cocoa the horse at Cowgirl Kate's door in another favorite stories edition for Green Light Readers Level 2 from the Geisel Honor-winning team of Erica Silverman and Betsy Lewin. AGES: 4 to 7 AUTHOR: Erica Silverman is the author of the Cowgirl Kate and Cocoa early reader books, the first of which received a Theodor Seuss Geisel Honor. Lana's World is her newest easy reader series. She has also written many picture books for children, including When the Chickens Went on Strike, Big Pumpkin, Hanukkah Hop, and Don't Fidget a Feather.