Media type: E-Article Title: Lecture Notes in Computer Science: Semantics and proof rules for coroutine hierarchies in block-structured programming languages Contributor: Raulefs, Peter imprint: Springer Berlin Heidelberg, 1977 Published in: Lecture Notes in Computer Science Language: Not determined DOI: 10.1007/3-540-08353-7_167 ISSN: 0302-9743; 1611-3349 Origination: Footnote: