What are the description and credit of the course which the student whose last name is Smithson took?
select t4.crs_description, t4.crs_credit from class as t1 join enroll as t2 on t1.class_code = t2.class_code join student as t3 on t3.stu_num = t2.stu_num join course as t4 on t4.crs_code = t1.crs_code where t3.stu_lname = 'Smithson'