diff --git a/bin/structure.pl b/bin/structure.pl
index e755149..a435997 100644
--- a/bin/structure.pl
+++ b/bin/structure.pl
@@ -2,6 +2,11 @@
 use ISO_10303_21::Grammar;
 use ISO_10303_21::Actions;
 
+sub print-sorted-keys(%look-for) {
+    say "Looking for " ~ %look-for.keys.sort(-> $a, $b { substr($a, 1) <=> substr($b, 1) }).join(" ");
+    
+}
+
 for @*ARGS -> $file {
     say "Reading $file";
     my $file-data = slurp($file);
@@ -13,17 +18,43 @@
         next;
     }
     
-    my @look-for;
+    my %look-for;
     for $step-data.entities.kv -> $index, $object {
         if $object ~~ ISO_10303_21::Record {
             if $object.keyword ~~ /SHAPE_REPRESENTATION$/ {
-                @look-for.push($index);
+                %look-for{$index} = 1;
             }
         } else {
             if any($object.list.map({ $_.keyword ~~ /SHAPE_REPRESENTATION$/ })) {
-                @look-for.push($index);
+                %look-for{$index} = 1;
             }
         }
     }
+
+    print-sorted-keys(%look-for);
+
+    my $previous-count = 0;
     
+    while $previous-count != +%look-for {
+        $previous-count = +%look-for;
+        for $step-data.entities.kv -> $index, $object {
+            if $object ~~ ISO_10303_21::Record {
+                for $object.entity_instances -> $reference {
+                    if %look-for{$reference} {
+                        %look-for{$index} = 1;
+                    }
+                }
+            } else {
+                for @($object) -> $object {
+                    for $object.entity_instances -> $reference {
+                        if %look-for{$reference} {
+                            %look-for{$index} = 1;
+                        }
+                    }
+                }
+            }
+        }
+        print-sorted-keys(%look-for);
+    }
+   
 }
\ No newline at end of file