U.S. PATENT DOCUMENTS 3,930,022 12/1975 Hawk et al. ........................ 424/330 4,076,843 2/1978 Hauck et al. ........................ 424/330 4,087,545 5/1978 Archer et al. ....................... 424/283 4,101,677 7/1978 Dunnigan et al. .................. 424/330 4,163,063 7/1979 Cannon et al. ...................... 424/330 4,228,169 10/1980 Johnson et al. ..................... 424/258 4...