The reference you are looking for regarding maternal fluid intake
requirements is included in the Lawrence Third edition (blue book),
 Breastfeeding: a guide for the medical professsion.  Look on pages 228-229.
 A  similar reference to the same study cited is included in the WHO
Bulletin;Supplement Vol 67, 1989 page35

Liz Flight, RN, CLE, IBCLC
Jacksonville, Florida