Pekrun, W. (1983). Free semigroup-theoretical word problems for given degree of unsolvability.
Chicago Style (17th ed.) CitationPekrun, Wolfgang. Free Semigroup-theoretical Word Problems for Given Degree of Unsolvability. 1983.
MLA (9th ed.) CitationPekrun, Wolfgang. Free Semigroup-theoretical Word Problems for Given Degree of Unsolvability. 1983.
Warning: These citations may not always be 100% accurate.