J. Nyeki, R. Ray, G. Sheshin, V. Maidanov, V. Mikheev, B. Cowan, and J. Saunders, Structure and superfluidity of ⁴He films on plated graphite, Low Temp. Phys. 23, (1997) [Fiz. Nizk. Temp. 23, 515-526, (1997)].