EXHIBIT A



                                                November 23, 1999






Liberty Group Holdings, Inc.
11 52nd Street
Brooklyn, New York  11232


            Re:   Shares of common stock,  par value $.004 per share ("Common
                  Stock")   of   Liberty   Group   Holdings,   Inc.,   f/k/a
                  Bio-Response, Inc. (the "Company")

Gentlemen:

            The  undersigned  is the  record and  beneficial  owner of shares of
Common Stock (the "Shares")  which were issued to the undersigned by the Company
for valid consideration on November 23, 1999.

            The undersigned  hereby agrees and acknowledges,  for the benefit of
the Company and its successors and assigns, that (a) the undersigned has not and
will not be directly or  indirectly  involved in any activity  that  promotes or
otherwise  maintains  a  market  for  the  securities  of the  Company;  (b) the
undersigned  will not  engage  in any  "buy-side"  trading  activities,  hedging
transactions or other  activities that could reasonably be expected to influence
the market price of the securities of the Company; (c) the undersigned shall not
sell,  transfer,  gift or otherwise  dispose of any of the Shares until November
24, 2001; and after such time, (i) the undersigned  shall not sell the Shares in
a  transaction  that is  effected  at a price which is lower than the quoted bid
price of the  Shares at the time of sale;  (ii) if the  undersigned  engages  in
multiple sales of Shares in any five (5)  consecutive  business day period,  the
undersigned  shall not sell any Shares in a  transaction  that is  effected at a
price  which is lower than the last price  received by the  undersigned  for the
Shares;  and (iii) the undersigned shall not sell more than ten percent (10%) of
the Shares held by the undersigned in any calendar month.

            This  letter  agreement  shall  be  governed  by  and  construed  in
accordance  with the laws of the State of New York. All actions and  proceedings
arising out of or relating to this letter shall be heard and  determined  in any
state or federal court sitting in New York, New York.

            This  letter  shall be binding  upon and inure to the benefit of the
parties  hereto  and  their  respective  successors  and  assigns,  and  if  the
undersigned is an individual, to his or her heirs and legal representatives.



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            If any provision of this letter  agreement  shall be held invalid or
unenforceable,  such  invalidity or  unenforceability  shall attach only to such
provision and only to the extent such  provision  shall be held to be invalid or
unenforceable  and shall not in any way affect the validity or  enforceablity of
the  other  provisions  hereof,  all of which  provisions  are  hereby  declared
severable,  and this letter agreement shall be carried out as if such invalid or
unenforceable provision or portion thereof was not embodied herein.

            This letter agreement is being delivered to you in duplicate. Please
execute and return one copy to the undersigned, whereupon it will constitute our
agreement with respect to the matters set forth above.


                              Yours truly,


                                WILLOW ROAD TRUST

                              By:____________________________
                                Name: Barry Hawk
                                 Title: Trustee

                              The Trustee  executes this document  solely in his
                              fiduciary capacity as the trustee of the Trust and
                              recourse against the Trust shall be limited solely
                              to the assets of the Trust and no  recourse  shall
                              be had against the Trustee thereof.