Systems

1990 • 56 Readers • 454 pages • 3.8

2017 • 47 Readers • 479 pages • 4

1972 • 32 Readers • 338 pages • 4.3

2017 • 160 Readers • 305 pages • 4.2

2008 • 294 Readers • 218 pages • 4.2

1993 • 19 Readers • 380 pages • 4.3

2001 • 1 Reader

1999 • 2 Readers • 312 pages

1953 • 1 Reader • 311 pages • 4

1984 • 5 Readers • 168 pages • 4