diff --git a/docs/LEARNING.md b/docs/LEARNING.md
index 3b0f32e9..af628445 100644
--- a/docs/LEARNING.md
+++ b/docs/LEARNING.md
@@ -6,8 +6,8 @@ For that reason, learning
 [the basic syntax of Tcl](https://tcl.tk/man/tcl8.6/TclCmd/Tcl.htm)
 is quite easy.
 
-For a hands-on tutorial, there is:
- - https://learnxinyminutes.com/docs/tcl/
+For a hands-on tutorial:
+ - [Learn X in Y minutes: Tcl](https://learnxinyminutes.com/docs/tcl/)
 
-For a comprehensive tutorial in more parts, there is:
- - https://www.tcl.tk/man/tcl8.5/tutorial/tcltutorial.html
+For a comprehensive tutorial in more parts:
+ - [the Tcl tutorial](https://www.tcl.tk/man/tcl8.5/tutorial/tcltutorial.html)
diff --git a/notes-on-unimplemented-exercises.md b/notes-on-unimplemented-exercises.md
index d6f9f58f..5b49e8c3 100644
--- a/notes-on-unimplemented-exercises.md
+++ b/notes-on-unimplemented-exercises.md
@@ -10,6 +10,7 @@
 
 ## Merely unimplemented
 
+* [killer-sudoku-helper][killer-sudoku-helper]
 * [ledger][ledger]
     - a tedious-to-create refactoring exercise
 * [lens-person][lens-person]
@@ -17,7 +18,9 @@
     - but this exercise could be about ways to access deeply nested dictionaries
 * [paasio][paasio]
     - probably need to use the [`transchan`][transchan] command
+    - [this stackoverflow question][tcl-tee] may provide a starting point
 * [sgf-parsing][sgf-parsing]
+* [state-of-tic-tac-toe][state-of-tic-tac-toe]
 * [tree-building][tree-building]
     - a tedious-to-create refactoring exercise
 
@@ -25,9 +28,12 @@
 [unimplemented]: https://tracks.exercism.io/tcl/main/unimplemented
 [lens-person]: https://github.com/exercism/problem-specifications/tree/master/exercises/lens-person
 [micro-blog]: https://github.com/exercism/problem-specifications/tree/master/exercises/micro-blog
-[tcl-unicode]: https://wiki.tcl-lang.org/page/Unicode+and+UTF-tree-building
+[tcl-unicode]: https://wiki.tcl-lang.org/page/Unicode+and+UTF-8
 [ledger]: https://github.com/exercism/problem-specifications/tree/master/exercises/ledger
 [paasio]: https://github.com/exercism/problem-specifications/tree/master/exercises/paasio
+[tcl-tee]: https://stackoverflow.com/q/72352064/7552
 [sgf-parsing]: https://github.com/exercism/problem-specifications/tree/master/exercises/sgf-parsing
 [tree-building]: https://github.com/exercism/problem-specifications/tree/master/exercises/tree-building
+[killer-sudoku-helper]: https://github.com/exercism/problem-specifications/tree/master/exercises/killer-sudoku-helper
+[state-of-tic-tac-toe]: https://github.com/exercism/problem-specifications/tree/master/exercises/state-of-tic-tac-toe
 [transchan]: https://www.tcl-lang.org/man/tcl8.6/TclCmd/transchan.htm