What is the most expensive book item? Please provide a short description of projects related to those.
book item refers to project_resource_type = 'Books'; most expensive refers to MAX(item_unit_price)
SELECT T1.item_name, T2.short_description FROM resources AS T1 INNER JOIN essays AS T2 ON T1.projectid = T2.projectid WHERE T1.project_resource_type = 'Books' ORDER BY T1.item_unit_price DESC LIMIT 1