Wikidata currently documents 37 million scholarly articles, and the number keeps increasing. It is hard to understand and analyze the main subjects and domains of these articles. Though Wikidata has a property P921 (main subject) which can help find relevant scientific articles of different domains on diverse topics, its current usage is limited to around 17 million (Scholia statistics). This talk focuses on the ongoing work on improving the links between scholarly articles and existing Wikidata items using P921, its advantages, and limitations.