1993ApJ...413..251S
1993ApJ...413..251S
1993ApJ...413..251S
1993ApJ...413..251S
1993ApJ...413..251S
1993ApJ...413..251S
1993ApJ...413..251S
1993ApJ...413..251S
1993ApJ...413..251S
1993ApJ...413..251S
1993ApJ...413..251S
1993ApJ...413..251S
1993ApJ...413..251S
1993ApJ...413..251S
1993ApJ...413..251S
1993ApJ...413..251S
1993ApJ...413..251S