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- Buku AudioCitadels Under AttackAlex Raymond
- Buku AudioThe Plague of SoundAlex Raymond
- Buku AudioThe Witch Queen of MongoAlex Raymond
- Buku AudioThe Time Trap of Ming XIIIAlex Raymond
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- Buku AudioThe War of the CybernautsAlex Raymond
- Buku AudioCitadels on EarthAlex Raymond
- Buku AudioCrisis on Citadel IIAlex Raymond
- Buku AudioMassacre in the 22nd CenturyAlex Raymond
- Buku AudioWar of the CitadelsAlex Raymond
- Buku AudioThe Space CircusAlex Raymond
- Buku AudioSeri: Flash GordonAlex Raymond