If you are referring to a specific known paper titled (or something similar) with exactly 26 pages, it is not a widely indexed publication in major databases (Google Scholar, Scopus, ACM, IEEE) under that exact title.
or a related technical report from his work at LIACC / University of Porto .
It seems you are looking for a specific paper (possibly a PDF of 26 pages) related to an by Helder Guimarães .
However, I cannot directly provide or link to a PDF file. Based on available academic records, Helder Guimarães has worked on ontology engineering, semantic web, and knowledge representation. The most likely paper matching your description is:
