If I do say so myself, I regard this compendium as exhaustive. I am fairly certain you won't locate any additional written reports prior to (say) 1950. The information is fully documented, and a number of maps are provided at the end.
As I was trolling through Australian newspaper files researching the previous book, I kept coming across reports from other parts of the world. Cross-checking them against Heuvelmans' list, I discovered that many of them had also been missed, overlooked, or ignored by previous researchers. It seemed to me I would be doing the cryptozoological world a favour were I to publish them in a single volume. But even I was surprised to discover they numbered more than 70. Heaven only knows how many others are out there, which never made it to the Australian press!
Anyway, this volume has been compiled as a service to you. Anybody looking for completeness in their data on this esoteric subject would be advised to acquire it.