What has the author JGH Tans written?

It appears you're asking about an author named "JGH Tans." While there may be authors with similar initials, there is no widely recognized author with those exact initials.

It's possible you've misremembered the author's name or initials. To help me find the author you're looking for, could you please provide:

* The full name of the author (if you know it)

* The title of any books they've written

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With more information, I can assist you in finding the author you're searching for.