diff --git a/papers/hatra21/bibliography.bib b/papers/hatra21/bibliography.bib
index 7a92741c..544c0941 100644
--- a/papers/hatra21/bibliography.bib
+++ b/papers/hatra21/bibliography.bib
@@ -50,3 +50,66 @@
   isbn =         {9781617293023},
 }
 
+@PhdThesis{TopQuality,
+  author =       {Bastiaan J. Heeren},
+  title =        {Top Quality Type Error Messages},
+  school =       {U. Utrecht},
+  year =         {2005},
+}
+
+@PhdThesis{RepairingTypeErrors,
+  author =       {Bruce J. McAdam},
+  title =        {Repairing Type Errors in Functional Programs},
+  school =       {U. Edinburgh},
+  year =         {2002},
+}
+
+@InProceedings{GradualTyping,
+  author =       {Jeremy G. Siek and Walid Taha},
+  title =        {Gradual Typing for Functional Languages},
+  booktitle =    {Proc. Scheme and Functional Programming Workshop},
+  year =         {2006},
+  pages =        {81-92},
+}
+
+@InProceedings{WellTyped,
+  author =       {Philip Wadler and Robert Bruce Findler},
+  title =        {Well-typed Programs Can’t be Blamed},
+  booktitle =    {Proc. European Symp. Programming},
+  year =         {2009},
+  pages =        {1-16},
+}
+
+@InProceedings{Contracts,
+  author =       {Robert B, Findler and Matthias Felleisen},
+  title =        {Contracts for Higher-order Functions},
+  booktitle =    {Proc. Int. Conf. Functional Programming},
+  year =         {2002},
+  pages =        {48-59},
+}
+
+@inproceedings{SuccessTyping,
+  author = {Lindahl, Tobias and Sagonas, Konstantinos},
+  title = {Practical Type Inference Based on Success Typings},
+  year = {2006},
+  booktitle = {Proc. Int. Conf. Principles and Practice of Declarative Programming},
+  pages = {167–178},
+}
+
+@InProceedings{IncorrectnessLogic,
+  author = {O'Hearn, Peter W.},
+  title = {Incorrectness Logic},
+  year = {2020},
+  booktitle = {Proc. Symp. Principles of Programming Languages},
+  articleno = {10},
+  pages = {1-32},
+}
+
+@Misc{HowToDrawAnOwl,
+  author =       {Know Your Meme},
+  title =        {How To Draw An Owl},
+  year =         {2010},
+  url =    {https://knowyourmeme.com/memes/how-to-draw-an-owl},
+}
+
+
diff --git a/papers/hatra21/hatra21.pdf b/papers/hatra21/hatra21.pdf
index ad727aa8..0741bff4 100644
Binary files a/papers/hatra21/hatra21.pdf and b/papers/hatra21/hatra21.pdf differ
diff --git a/papers/hatra21/hatra21.tex b/papers/hatra21/hatra21.tex
index 730fe00b..ce19d08f 100644
--- a/papers/hatra21/hatra21.tex
+++ b/papers/hatra21/hatra21.tex
@@ -163,7 +163,7 @@ Program analysis can still flag type errors, for example with red
 squiggly underlining. Formalizing this, rather than a judgment
 $\Gamma\vdash M:T$, for an input term $M$, there is a judgment
 $\Gamma \vdash M \Rightarrow N : T$ where $N$ is an output term
-where some subterms are \emph{flagged} $\squnder{N}$. Write $\erase(N)$
+where some subterms are \emph{flagged} as having type errors, written $\squnder{N}$. Write $\erase(N)$
 for the result of erasing flaggings: $\erase(\squnder{N}) = \erase(N)$.
 
 %% For example the usual
@@ -207,8 +207,12 @@ Some issues raised by infallible types:
   than genuine errors?
 \item How can the goals of an infallible type system be formalized?
 \end{itemize}
-Related work: lots on type error reporting~\cite{???}, and on
-heuristics for program repair~\cite{???}, but not type repair, or on
+\emph{Related work}:
+there is a large body of work on type error reporting
+(see, for example, the survey in~\cite[Ch.~3]{TopQuality})
+and on type-directed program repair
+(see, for example, the survey in~\cite[Ch.~3]{RepairingTypeErrors}),
+but not type repair, or on
 the semantics of programs with type errors. Many compilers perform
 error recovery during typechecking, but do not provide a semantics
 for programs with type errors.
@@ -242,7 +246,7 @@ Some issues raised by infallible types:
   ($\squnder{V} \rightarrow V$) the right one?
 \item Will higher-order code require wrappers on functions? 
 \end{itemize}
-Related work: blame analysis~\cite{???}.
+\emph{Related work}: gradual typing and blame analysis, e.g.~\cite{GradualTyping,WellTyped,Contracts}
 
 \subsection{Nonstrict types}
 
@@ -295,7 +299,7 @@ Some issues raised by nonstrict types:
   not \emph{contavariant}; what impact does this have?
   
 \end{itemize}
-Related work: success types~\cite{???} and incorrectness logic~\cite{???}.
+\emph{Related work}: success types~\cite{SuccessTyping} and incorrectness logic~\cite{IncorrectnessLogic}.
 
 \subsection{Mixing types}
 
@@ -325,14 +329,14 @@ Some issues raised by mixed-mode types:
   only with different flagging?
 
 \end{itemize}
-Related work: none???
+\emph{Related work}: this appears to be an undererxplored area.
 
 \section{Conclusions}
 
 In this paper, we have presented some of the goals of the Luau type
 system, and how they map to the needs of the Roblox creator
 community. We have sketched what a solution might look like, all that
-remains is to draw the damn owl~\cite{owl}.
+remains is to draw the owl~\cite{HowToDrawAnOwl}.
 
 \bibliographystyle{ACM-Reference-Format} \bibliography{bibliography}