Pine for 2 x extra shelves (Tysoe CV350S)

Hello. I’m hoping you could help 🙏 I would like a couple of extra shelves for my pine bookcase. It’s not super quality but it’s doing the job I need at the moment. The shelves measure 57 x 29 x 1.5 cm. Have you anything I could get an extra few shelves out of please. Thank you. Beverley