Pdf.js: bower 정의되지 않은 속성 'PDFJS'를 읽을 수 없습니다.

bower install pdfjs-dist

<script src="bower_components/pdfjs-dist/build/pdf.js"></script>
<script src="bower_components/pdfjs-dist/build/pdf.worker.js"></script>

Uncaught TypeError: Cannot read property 'PDFJS' of undefined
    at Object.defineProperty.value (pdf.js:14288)
    at __w_pdfjs_require__ (pdf.js:45)
    at Object._typeof (pdf.js:8065)
    at __w_pdfjs_require__ (pdf.js:45)
    at Object.defineProperty.value (pdf.js:88)
    at pdf.js:91
    at webpackUniversalModuleDefinition (pdf.js:24)
    at pdf.js:25