PROJECT OBERON, The Design of an Operating system and Compiler N. Wirth, J. Gutknecht ACM Press and Addison-Weseley Publishing Company, 1992 ISBN 0-201-54428-8
http://www.inf.ethz.ch/personal/wirth/books/ProjectOberon.pdf
Spirit-of-Oberon/ProjectOberonV4
All source texts from book "PROJECT OBERON, The Design of an Operating system and Compiler" N. Wirth, J. Gutknecht ACM Press and Addison-Weseley Publishing Company, 1992 ISBN 0-201-54428-8