Electronics Letters
Electronics Letters > 1986 > 22 > 17 > 915 - 917
Electronics Letters > 1991 > 27 > 17 > 1521 - 1523
Electronics Letters > 1992 > 28 > 8 > 771 - 773
Electronics Letters > 1992 > 28 > 17 > 1608 - 1610
Electronics Letters > 1993 > 29 > 4 > 387 - 389