from typing import List


def feeds_ioc_mentioned_in(ioc_value: str, df) -> List[str]:
    """Return feed names where specified IOC was mentioned in"""
    feeds: List[str] = []
    for feed in df:
        is_ioc_exist = feed["df"].loc[feed["df"]["value"] == ioc_value]
        if not is_ioc_exist.empty:
            feeds.append(feed["name"])
    return feeds