...
type
   Tinf = string [20];
   Ttree = ^TNode;
   TNode = record
                inf: Tinf;
                left, right: Ttree;
           end;
   Tptr = ^Tlist;
   Tlist = record
                inf: Tinf;
                next: tptr;
             end;
   TQueue = record
                 head,
                 tail: Tptr;
             end;
...
function Find(Root: TTree; X: Tinf): TTree;
q: Tqueue;
begin
   if Root = nil then Find := nil
   else
    if X = Root^.inf then Find := Root
    else
     if X < Root^.inf then Find := Find(Root^.Left, X)
      else Find := Find(Root^.Right, X);
end;

...
type
Tinf = string [20];
Ttree = ^TNode;
   TNode = record
                inf: Tinf;
                left, right: Ttree;
           end;
   Tptr = ^Tlist;
   Tlist = record
                inf: Tinf;
                next: tptr;
             end;
   TQueue = record
                 head,
                 tail: Tptr;
             end;