1. Nothing's plenty: the vacuum in modern quantum field theory;Aitchison;Contemporary Physics,1985
2. De anima;Aristotle,1908
3. The nature of developmental stages;Bickhard;Human Development,1978
4. Cognition, convention, and communication;Bickhard,1980
5. A model of developmental and psychological processes;Bickhard;Genetic Psychology Monographs,1980