Appendix where Gandalf and the hobbits discuss their adventure
 

Some time ago someone here at BD posted a link to an appendix written by JRRT where Gandalf and the hobbits are discussing the aftermath of their adventures. I believe Merry asks him what caused him to choose Bilbo to accompany the dwarves to Erebor and Gandalf goes on to explain some of the decisions he had to make leading up to their quest.

Could someone please tell me in which book this appendix can be found, and perhaps the link also?

Thank you.

Don't know about the link, but a part of the discussion is (briefly) included in LotR itself; in Appendix A, III: Durin's Folk, and in larger length in the Unfinished Tales - the whole chapter "Quest of Erebor".

About the link, I guess its illegal to post links to copyrighted works on the net...I mean I don't care about other authors, but at least in Tolkien's case you could go buy the book.

You're referring to the text "The Quest of Erebor" of which there are four known versions, three of which are in print. As said above, the last, very condensed, version is in Appendix A. A longer narrative was printed in Unfinished Tales (with descriptions of the variant versions); and yet a third appears in the 2nd Edition of Doug Anderson's "Annotated Hobbit."

Don't confuse this 'appendix' with the Epilogue Tolkien wrote for LotR but also left out, which is a whole other, er, thing......

I'd say the one to look at is The Quest of Erebor in the Unfinished Tales...

It's in the Unfinished Tales. I know this because I have the book and I've read the chapter The Quest for Erebor. I hope that was helpful.