import requests


def get_dois(issn, from_year, to_year):
    """
    Returns a list of DOIs for a particular timeframe.
    """
    dois = []
    url = f"https://api.crossref.org/journals/{issn}/works?rows=500&filter=from-pub-date:{from_year}-01-01,until-pub-date:{to_year}-01-01&mailto=team@ourresearch.org"
    r = requests.get(url)
    if r.status_code == 200:
        for article in r.json()["message"]["items"]:
            dois.append(article["DOI"])
    return dois