Add links.

README.md

@@ -194,6 +194,17 @@ Talos II ppc64el machine running Debian bullseye.
 The apt canary sites mentioned for Trisquel, PureOS, Ubuntu, Debian
 and Devuan are updated manually, which is a bit of a bottle-neck.
 
+## Related work
+
+Some related efforts:
+
+- https://github.com/sigstore/rekor
+- https://www.sigsum.org/
+- https://arxiv.org/abs/1711.07278
+- https://github.com/FreeBSDFoundation/binary-transparency-notes
+- https://debconf17.debconf.org/talks/153/
+- https://wiki.debian.org/Derivatives/Integration#Patches
+
 ## Further work
 
 This is a proof-of-concept project that does something useful in some