diagram of the plumbing $N_{m,n}$ as a surgery diagram for $Y_{m,n}$, we derive the Heegaard diagram of its boundary. A disk bundle over a sphere is given by a single framed circle, and a double plumbing of two such bundles is represented by the Kirby diagram in Figure \[fig:kirby\]. The second plumbing contributes a 1-handle. Instead of adding the 1-handle one can remove its complementary 2-handle with framing zero. The boundary of the resulting manifold remains unchanged if we replace the 1-handle by its complementary 2-handle with framing zero and obtain a Kirby diagram which is a link of three framed unknots $K_{1},K_{2}$ and $K_{3}$ in $S^{3}$.

$K_{1}$ at 120 440 $K_{2}$ at 700 440 $K_{3}$ at 400 320 $S^{2}$ at 800 190 $m$ \[b\] at 310 460 $n$ \[b\] at 530 460

![The Kirby diagram of a double plumbing[]{data-label="fig:kirby"}](dvakratnipp)

To obtain the Heegaard diagram of the boundary, we split the 3-sphere into two balls along the sphere $S^{2}$ shown in Figure \[fig:kirby\]. Surgery along the three framed circles $K_{i}$ gives us two handlebodies of genus 3. The Heegaard diagram is drawn on the plane with three 1-handles added. The lower handlebody is a boundary connected sum of regular neighborhoods 