D14 Tree Study V, Tate London (T09309)
D10 Tree Study I, Tate, London (T09307)
D12 Tree Study III, Tate, London (T09308)
D13 Tree Study IV, Tate, London (T09311)
D388 Trtee Study The National Library of Wales, Aberystwyth / Llyfrgell Genedlaethol Cymru