There's a lot of useful stuff in the Mailmerge Tips & Tricks 'Sticky' thread at this forum's top:
https://www.msofficeforums.com/mail-...ps-tricks.html
A lot of that material is unlikely to be in any book you could buy - and here 'tis for FREE!

Beyond that, if you're interested in:
Date Calculations:
check out my Microsoft Word Date Calculation Tutorial, at:
http://windowssecrets.com/forums/sho...ation-Tutorial
or:
http://www.gmayor.com/downloads.htm#Third_party
Although not written specifically for mailmerges, the field codes there are readily adapted to that purpose.


Word Field Maths:
check out my Microsoft Word Field Maths Tutorial, at:
http://windowssecrets.com/forums/sho...Maths-Tutorial
or:
http://www.gmayor.com/downloads.htm#Third_party
Although not written specifically for mailmerges, the field codes there are readily adapted to that purpose.


Catalogue/Directory Mailmerges:
check out my Microsoft Word Catalogue/Directory Mailmerge Tutorial at:
http://windowssecrets.com/forums/sho...merge-Tutorial
or:
http://www.gmayor.com/Zips/Catalogue%20Mailmerge.zip

The tutorial covers everything from list creation to the insertion & calculation of values in multi-record tables in letters. Do read the tutorial before trying to use the mailmerge document included with it.


For some worked examples, see the attachments to the posts at:
https://www.msofficeforums.com/mail-...html#post23345
https://www.msofficeforums.com/mail-...html#post30327
http://windowssecrets.com/forums/sho...l=1#post928391

As the foregoing will show, the scope for what can be done in a mailmerge is quite extensive. Beyond what you'll read in those resources, though, still quite a lot more to learn and a lot of what can be achieved depends on using both your knowledge and imagination.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]