://github.com/JustinMShea/wooldridge/blob/HEAD/R/card.R" class="external-link"><code>R/card.R</code></a></small>
    <div class="hidden name"><code>card.Rd</code></div>
    </div>

    <div class="ref-description">
    <p>Wooldridge Source: D. Card (1995), Using Geographic Variation in College Proximity to Estimate the Return to Schooling, in Aspects of Labour Market Behavior: Essays in Honour of John Vanderkamp. Ed. L.N. Christophides, E.K. Grant, and R. Swidinsky, 201-222. Toronto: University of Toronto P