참고자료.md

 ## [우주선](우주선)
 
-1. [APOLLO 17 LUNAR SURFACE COSMIC RAY DETECTOR NASA Contract](https://ntrs.nasa.gov/api/citations/19740019764/downloads/19740019764.pdf)
+1. [Walker, R. M. (1974). APOLLO 17 LUNAR SURFACE COSMIC RAY DETECTOR Final Report. Washington University. NASA-cR-134329](https://ntrs.nasa.gov/api/citations/19740019764/downloads/19740019764.pdf)
 
 2. [Primary Cosmic Rays on the Lunar Surface](https://ntrs.nasa.gov/api/citations/19780005025/downloads/19780005025.pdf)