Bernd & Hilla Becher, ‘Four works: (i) Zimmermann Coal Co., Ravine, Schuylkill Country; (ii) Scade Coal Co., Goodspring Mountains, Schuylkill Country; (iii) Scheib & Walacavage, No. 2, Joliett, Schuykill Country; (iv) Minnich Coal Co., Goodspring Mountains, Schuykill Country’, 1983, Phillips