Beach RS, Borchers JA, Salamon MB, Du R, Flynn CP. Observation of intermediate spin states in Er/Y superlattices. Journal of Applied Physics. 1990;(9):5710-5712.

Du R, Flynn CP. Asymmetric coherent tilt boundaries formed by molecular beam epitaxy. Journal of Physics: Condensed Matter. 1990;(5):1335-1341.