diff --git a/diffeomorphic_approx_3d_lp_le2_v2.txt b/diffeomorphic_approx_3d_lp_le2_v2.txt
index 2c0b336..3a37ddc 100644
--- a/diffeomorphic_approx_3d_lp_le2_v2.txt
+++ b/diffeomorphic_approx_3d_lp_le2_v2.txt
@@ -61,22 +61,45 @@ the Sobolev norm.
 
 ./ball-2001-singularities-computation-minimizers.pdf
 
-History, in one paragraph. In the plane, Iwaniec, Kovalev and Onninen
-proved strong approximation for 1 < p < infinity, and Hencl and
-Pratelli added the endpoint p = 1. In higher dimensions the answer is
-NO for small p: Campbell, Hencl and Tengvall show that in dimension
-n >= 4 and for 1 <= p < floor(n/2) there is a W^{1,p} homeomorphism
-whose Jacobian takes both signs on sets of positive measure; a limit of
-diffeomorphisms cannot reproduce that sign pattern. In dimension 3
-the orientation obstruction disappears: Hencl and Maly show that a
-sense-preserving W^{1,1}_loc homeomorphism in R^3 has det Df >= 0
-almost everywhere. Theorem A says that in R^3 the only remaining
-obstruction is gone for 1 <= p <= 2. The complementary range
-  2 < p < infinity in R^3 calls for a separate construction.
+In the plane, Iwaniec, Kovalev and Onninen proved strong approximation
+for 1 < p < infinity, Hencl and Pratelli added the endpoint p = 1, and
+Daneri and Pratelli controlled the bi-Lipschitz case with both forward
+and inverse derivative errors. In higher dimensions the answer is NO
+for small p: Campbell, Hencl and Tengvall show that in dimension n >= 4
+and 1 <= p < floor(n/2) there is a W^{1,p} homeomorphism whose Jacobian
+takes both signs on sets of positive measure; a limit of diffeomorphisms
+cannot reproduce that sign pattern. In dimension 3 the orientation
+obstruction disappears: Hencl and Maly show that a sense-preserving
+W^{1,1}_loc homeomorphism in R^3 has det Df >= 0 almost everywhere.
+Theorem A says that in R^3 the only remaining obstruction is gone for
+1 <= p <= 2. The range 2 < p < infinity requires a separate construction.
+
+The smoothing step alone, where a piecewise affine homeomorphism is
+approximated by a smooth diffeomorphism, has its own literature.
+Vaisala developed piecewise linear approximation of lipeomorphisms.
+Mora-Corral and Pratelli obtained fixed-image diffeomorphic smoothing
+in the plane for piecewise affine maps. Campbell and Soudsky proved
+C^1 homeomorphic approximation of piecewise affine maps in arbitrary
+dimension, without requiring smooth inverse. Campbell, D'Onofrio and
+Vitek proved diffeomorphic smoothing of locally finite piecewise
+affine homeomorphisms in dimensions three and four, with forward and
+inverse derivative-error control. These identify the importance of
+distinguishing a smooth injective map from a diffeomorphism. Hencl's
+recent survey records progress and open problems in the Ball-Evans
+question, following Ball's own account of the nonlinear-elasticity
+motivations.
 
 ./iwaniec-kovalev-onninen-2011-diffeomorphic-approx.pdf
+./iwaniec-kovalev-onninen-2012-hopf-differentials.pdf
+./daneri-pratelli-2011-bi-lipschitz-approx.pdf
 ./campbell-hencl-tengvall-2018-jacobian-signs.pdf
 ./hencl-maly-2010-jacobians-sobolev-homeos.pdf
+./vaisala-1977-pl-approximation-lipeomorphisms.pdf
+./mora-corral-pratelli-2014-pam-approx.pdf
+./campbell-soudsky-2021-smooth-homeomorphic-approx.pdf
+./campbell-donofrio-vitek-2026-diffeomorphic-approx-pam.pdf
+./hencl-2025-survey-sobolev-homeos.pdf
+./ball-2010-progress-puzzles-nonlinear-elasticity.pdf
 
 Throughout, a domain is a nonempty connected open set. All domains,
 closures, and compactness statements are relative to the ambient open
@@ -176,13 +199,13 @@ derivative estimates. The classical inputs are:
         Farb-Margalit 2012: classification of mapping classes of a
         punctured sphere, peripheral-preserving Dehn-Nielsen form.
 
-        Schoenflies, mapping class groups: the star replacement
-        described later.
+        Hatcher 2002: the Brouwer degree and the van Kampen theorem,
+        as classically presented.
 
 ./hamilton-1976-triangulation-3-manifolds.pdf
 ./papakyriakopoulos-1957-dehns-lemma-asphericity-knots.pdf
-./smale-1959.pdf
 ./li-watts-2011-s2-diffeos-so3.pdf
+./hatcher-2002-algebraic-topology.pdf
 
 These supply EXISTENCE of a homeomorphic replacement. They do not
 estimate its derivative: a PL approximant might have arbitrarily large
@@ -1620,6 +1643,8 @@ The classical inputs are listed once and for all:
 
         Dehn's lemma (Papakyriakopoulos 1957);
 
+        Brouwer degree and van Kampen (Hatcher 2002);
+
         classification of mapping classes of punctured spheres,
         peripheral-preserving Dehn-Nielsen form (Farb-Margalit 2012,
         Theorem 8.8 and Proposition 3.19);