Best all around book on koi health & diseases
by
Erik L. Johnson, DVM

Site planning, construction & maint. of healthy water gardens
by
Helen Nash

Design & maintenance, care, fish health
by
Philip Swindells

Maintaining & keeping a healthy pond; trouble shoot problems
by
Helen Nash

Water garden design, care, fish health
by
James Allison

Building ponds step-by-step
by
Jeff Reid