Laura Bow series

In Dr. Brain

 * In Dr. Brain hintbook may be a couple of references to Laura Bow games. Including Monocle, Lantern (may also be a KQ4 reference), Handkerchief of LB1.
 * Another puzzle in the same book also includes the 'monocle' reference.
 * A picture of Crodfoller T. Rhubarb can be found inside Island of Dr. Brain.

Hoyle series

 * Dr. Brain and Laura Bow appear in Hoyle 4.

In other works

 * Rosella's First Quest