{
    "query": {
        "category": "Mathematics",
        "publication_date": "1991-01",
        "nr_of_items": 1
    },
    "items": [
        {
            "title": "An Introduction to General Relativity",
            "subtitle": null,
            "author": "L. P. Hughston; K. P. Tod",
            "isbn": "9780521339438",
            "publisher": "Cambridge University Press",
            "link_to_publisher": "https:\/\/www.cambridge.org\/core\/books\/an-introduction-to-general-relativity\/21FCE3A071B91D7DF798C0357FCBF31D"
        }
    ]
}