+ wishlist Add to Cart The item has been added Author: Filippo Gazzola Hans-Christoph Grunau Guido Sweers Polyharmonic Boundary Value Problems: Positivity Preserving and Nonlinear Higher Order Elliptic Equations in Bounded Domains (Lecture Notes in Mathematics #1991) [9783642122446] Buy More - Save More. Below are the available bulk discount rates for each individual item when you purchase a certain amount Quantity Price Savings 25 - 49 12% 50 - 99 13% 100+ 14% List Price As Low as $84.99 Format: Paperback