 <p>Generally, nowadays you shouldn't ever need to manually add <code>/// &lt;reference...</code> references. If you've got your type definitions installed using NPM then they should be automatically included in your compilation process.</p> <p>All you need to do is import the module and start using it. For example, in a new empty test project I've just installed xlsx (<code>npm install xlsx @types/xlsx</code>) and I can now successfully compile and run the below:</p> <pre><code>import xlsx = require("xlsx"); var workbook = xlsx.readFile("test.xlsx"); </code></pre> <p>That should be all you need.</p>