One is 8c, and has 2 stamps, one date from 1973 and one date from 1975 (10c) the second with 2 dates, 1973 8 cent and 1975 10 cent, Viking 2, Decade of space 1971, Sarzin 1971 First day issue,  Pioneer II Feb 28 1975, Pioneer Feb 28 1975, Mariner 10 APr 4 1975, Apollo  ASTP Link Up, July 17, 1975 and last is Bicentenary Feb 23 1976 with metal Cache on front and an extra on the back as shown.  Most in NM condition.  Some have discoloration and slight staining, ASTP has bends as shown.   Please see pictures for condition.