Contribution: This study presents the results of a systematic mapping on the classification and organization of open educational resources (OERs) focused on Computer Science Education (CSEd) in digital sources. Background: The number of open resources (e.g., images, videos, and websites) available on the Internet for the teaching of Computer Science has increased in recent years. As a consequence, several authors have proposed different ways of classifying them, which include lists of disciplines, classification algorithms, and semantic enrichment. However, such studies are dispersed and fragmented in the literature, making the current state-of-the-art unclear. Research Questions: (1) What digital sources have been used to classify OERs for CSEd? (2) What CSEd domains have been explored for the classification of OERs? and (3) What approaches have been adopted for the classification of OERs for CSEd? Methodology: Three search strategies were performed: (1) automatic search in the five major digital libraries of CSEd; (2) manual search in the major CSEd conferences and journals; and (3) snowballing on the references and citations. As a result, 22 relevant studies were selected. Findings: The main findings were systematization of the main OER sources for CSEd, identification of 64 CSEd domains covered by OERs organized in a taxonomy, the immaturity level of investigations and tools, and lack of mechanisms that organize OERs for CSEd.