1. G.K. Semin, A.V. Narygin and A.A.Boguslavsky, Izvestia AN USSR, Phys.,49 (1985) 1412.
2. E.A. Kravchenko et al., XI Int. Symposium NQR. London, 1991, Abstracts, p1:37.
3. H.A. Harwig, Z. anorg. alg. Chem.,444 (1978) 151.
4. A.V. Volkozub et al., Fizika tverdogo tela,33 (1991) 2506.
5. A. Schenck,Muon Spin Rotation Spectroscopy (Adam Hilger Ltd, Bristol, 1985)