1. Foundation of potato ridge riddling experiments;Palmer;Nat. Inst. agric. Engng Scottish Station SSN/154,1974
2. A research tool for the investigation of the relative effectiveness of various riddling motions;Milner;Nat. Inst. agric. Engng Scottish Station SSN/160,1974
3. Preliminary series of tests using experimental soil riddle;Palmer;Nat. Inst. agric. Engng Scottish Station SSN/162,1974