Abstract: | ![]() The original version of the article was published in Cent. Eur. J. Phys., Vol. 4(4), (2006), pp. 494-502. It can be also found online at: http://dx.doi.org/10.2478/s11534-006-0027-9. Unfortunately, the original version of this article contains mistakes in the numbering of its references. The reference numbers should be changed according to the following table: 1 | 9 | [2, 5, 7, 13-15] | [2, 5, 7, 13-16] | 2 | 5 | [2, 3, 7-10, 12, 17] | [2, 3, 7-10, 12, 18] | 2 | 7 | [2, 4, 5, 7, 14, 17] | [2, 4, 5, 7, 14, 18] | 2 | 9 | [11, 17] | [11, 18] | 2 | 13 | [18] | [19] | 2 | Footnote | [16] | [17] | 3 | 21 | [4, 5, 7, 14, 19] | [4, 5, 7, 14, 20] | 5 | 10 | [20] | [21] | 7 | 17 | [21] | [22] | 7 | 23 | [14, 15] | [15, 16] | The online version of the original article can be found at |