Cline, R.A. and van der Burgt, Peter J.M. and Westerveld, W.B. and Risley, J.S. (1994) Measurement of the H(n=2) density matrix for 20–100-keV collisions of H+ on He. Physical Review A, 49 (4). pp. 2613-2629. ISSN 1050-2947

Ligtenburg, R.C.G. and van der Burgt, Peter J.M. and Renwick, S.P. and Westerveld, W.B. and Risley, J.S. (1994) Optical oscillator strengths of noble-gas resonance transitions in the vacuum-ultraviolet region. Physical Review A, 49 (4). pp. 2363-2380. ISSN 1050-2947

Ashburn, J.R. and Cline, R.A. and van der Burgt, Peter J.M. and Westerveld, W.B. and Risley, J.S. (1990) Experimentally determined density matrices for H(n=3) formed in H+-He collisions from 20 to 100 keV. Physical Review A, 41 (5). pp. 2407-2421. ISSN 1050-2947

Ashburn, J.R. and Cline, R.A. and Stone, C.D. and van der Burgt, Peter J.M. and Westerveld, W.B. and Risley, J.S. (1989) Experimental determination of the H(n=3) density matrix for 80-keV H+ on He. Physical Review A, 40 (9). pp. 4885-4901. ISSN 1050-2947

van der Burgt, Peter J.M. and Westerveld, W.B. and Risley, J.S. (1989) Photoemission Cross Sections for Atomic Transitions in the Extreme Ultraviolet due to Electron Collisions with Atoms and Molecules. Journal of Physical and Chemical Reference Data, 18 (1757). ISSN 0047-2689