diff --git a/README.md b/README.md
index 882846b..967e502 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@
 ### doomsday-fuel
 * Completed in: 2 days, 19 hrs, 36 mins, 16 secs.
 * Reference
-  * L26.6 Absorption Probabilities, MIT OpenCourseWare, https://www.youtube.com/watch?v=vEsUsaK1HBk
+  * [L26.6 Absorption Probabilities, MIT OpenCourseWare](https://www.youtube.com/watch?v=vEsUsaK1HBk)
 
 ### the-grandest-staircase-of-them-all
 * Completed in: 16 hrs, 38 mins, 52 secs.
@@ -31,8 +31,9 @@
 ### dodge-the-laser
 * Completed in: 2 days, 20 hrs, 22 mins, 39 secs.
 * References
-  * [Beatty sequence](https://en.wikipedia.org/wiki/Beatty_sequence)
-  * How to find A001951 A Beatty sequence: a(n)=floor(n\*sqrt(2)), stackexchange, https://math.stackexchange.com/questions/2052179/how-to-find-sum-i-1n-left-lfloor-i-sqrt2-right-rfloor-a001951-a-beatty-s
+  * [Beatty sequence, Wikipedia](https://en.wikipedia.org/wiki/Beatty_sequence)
+  * [How to find A001951 A Beatty sequence: a(n)=floor(n\*sqrt(2)), StackExchange](https://math.stackexchange.com/questions/2052179/how-to-find-sum-i-1n-left-lfloor-i-sqrt2-right-rfloor-a001951-a-beatty-s)
+  * [Beatty Sequence와 Rayleigh's theorem, blog](https://tamref.com/36)
 * Feedback
   > [level5/dodge-the-lasers] (1) Some of the text readme.txt are duplicated. (2) Though the input type is string, Java input example uses quotes for string instead of double quotation marks. (3) While expected output type is string, in the output example does not use quotes. So the readers can confuse the return type.