diff --git a/README.md b/README.md
index aaedeb4..b106c91 100644
--- a/README.md
+++ b/README.md
@@ -15,6 +15,7 @@ The following criteria for knots periodicity were implemented:
 
 For a given list of knots [encoded in PD-code](http://katlas.org/wiki/Planar_Diagrams) (an input file is required) the script generates output with results for each criterion.
 
+
 -----
 
 We tested all knots up to 15 crossings and for the periodicity 3, 5, 7, 9, 11.
@@ -33,6 +34,7 @@ We tested all knots up to 15 crossings and for the periodicity 3, 5, 7, 9, 11.
 ### Input data
 
 Files with PD-codes for all knots up to 15 crossing are available in the repository (`knots_11_15.txt` and `knots_3_10.txt`) and should be saved in the same folder as the script or a path in the `class MySettings` should be adjusted. Similarly, if other input files will be used, settings have to be changed. A correction in parsing or reading functions may be also necessary (`check_11_to_15()`, `check_up_to_10()`, `parse_pd_code()`, `parse_knot_name()`).
+Data with PD-codes and HOMFLYPT polynomials are also available at [KnotInfo: Table of Knot Invariants, http://www.indiana.edu/~knotinfo](http://www.indiana.edu/~knotinfo/).
 
 ### Versions