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Weak subobjects and weak limits in categories and homotopy categories Marco Grandis (1997) Cahiers de Topologie et Géométrie Différentielle Catégoriques
When projective does not imply flat, and other homological anomalies. Lewis, Gaunce L.jun. (1999) Theory and Applications of Categories [electronic only]
Whitney continua of graphs admit all homotopy types of compact connected ANRs Hisao Kato (1988) Fundamenta Mathematicae