This link will direct you to Recent international books about aquatic therapy 

Dorpmans J, & Lambeck J. (1992). Only in Dutch, but still available:

Zwemmen met gehandicapten
Haarlem: De Vrieseborch
ISBN: 90-6076-356-4

Lambeck J. (1990). Proceedings of the International Halliwick conference in Nijmegen, NL. 
Halliwick in 1986: the realities of movement in water
Berg en Dal: Stichting NDT Nijmegen, ISBN 90-800538-1-3

a. introduction
aa. 4 Aspects...Mac
b. Hydrostatic.. van Gent'
c. Animal...Videler
d. The control...Roberts
e. Motor learning...Bernards
f. Muscle tone...Clarys
g. Current ideas...Mulder
h. Brain plast...Cools
i. Orientation...Ross
j. Rehabilitation...Haberfellner
k. A case...Bauer-Lasserre
l. A multidisc...Green
m. Group...Sharp
n. Scuba...Galligan

McMillan, J. The role of Water in Rehabilitation. Fysioterapeuten, 45: 43-46, 87-90, 236-240, 1977
The role of Water in Rehabilitation

Nicol, K., M. Schmidt-Hansberg, J. McMillan. Biomechanical Principles Applied to the Halliwick Method of Teaching Swimming to Physically Handicapped Individuals. In: Swimming III, red. J. Terauds, E.W. Bedingfield, Human Kinetics, 1979.
Biomechanical Principles Applied to the Halliwick Method of Teaching Swimming to Physically Handicapped Individuals

The Halliwick Method, J.Lambeck & F. Stanat
Part 1: AKWA, volume 15, June/July 2001, 39-41
Part 2: AKWA, volume 14, August/September 2001, 39-42
The Halliwick Method, J.Lambeck & F. Stanat