Please find the next book move

Using the analysis tool, I was trying to learn all book moves associated with a specific opening's variation. Here goes the Ruy López Opening: Morphy Defense, Caro, Graz Variation. Can anyone please tell me the next move for white. I want to know the book moves specifically, not any good or best move. Is there any book move after Bc5 on white's turn?

Most lines do not have only ONE book move... they usually have two or more alternatives.

In this case, 6. 0-0 and 6. c3 are played almost equally often, with similar results.

6. c3 might be just a bit more accurate.

But Chess.Com analysis tool doesn't show c3 as book move. Someone please help. 

I have no opening encyclopedia. 

https://www.365chess.com/opening.php

Is the chess.com analysis tool some sort of expert? I thought it was pretty retarded.

Now I see that there is no prescribed opening moves after Bc5. White may play the excellent move a4 or c3 which is the best move or castling King-side which is also the best move alternative to c3. If anything more is there then let me know.

Don't rely on the chess.com analysis tool for finding "book" moves.

Take this game of mine for example. How many of my moves were "book"?

https://www.chess.com/analysis/game/daily/200865884

The chess.com tool says only the first EIGHT moves were book.

In fact, the first TWENTY-EIGHT moves were book. Check Sznapik v. Ljangov, Sandomeirtz Poland 1976.

That tool is useless for any serious study. It's a "tool" for hobbyists.

@blueemu, I strongly defer. In spite of admitting that your moves (in your game which follows Sicilian Defense : Open, Scheveningen, Sozin, Flank Variation - 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 e6 6.Bc4 a6 7.Bb3 b5 8.O-O Be7) are given somewhere in some books since they are playable but book moves are something else. The variation mentioned in this thread has claimed book moves till Bc5. Your prescribed 365chess.com opening explorer also says the same as found to me by Chess.Com analysis tool. Kindly navigate to https://www.365chess.com/view_opening.php?n=3080. And thanks for paying attention to this post. Thank you so much. I would love to get you as my friend. I need only those friends here who love to talk on chess. Stay home and stay safe.

I had a look at van der Sterren's Fundamental Chess Openings (which is a general opening theory book, not going through all side lines) and it does not consider 5. ... Bc5 as theory, only 5. ... Na5. If you insert 4. ... Nf6 5. 0-0 and continue as before 5. ... b5 6. Bb3 Bc5, you arrive to the Neo-Arkhangelsk variation, where the two book moves are 7. c3 and 7. a4. So I guess the moves you already have found are the most solid options.

Thanks @harriw. You are another Chess.Com user showing keen interest to chess. Would you please post the moves here? Are you talking about Ruy López Opening: Morphy Defense, Neo-Arkhangelsk Variation
1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.O-O Bc5? If not, then post please.

I'm sure I castled after I'd been in check,?

BlueEmu is right.  The concept of "Book Moves" on chess.com is utter garbage!

Take the following game:

https://www.chess.com/analysis/game/live/4748054407

Chess.com claims Black's 5th move is dubious and that this game was book moves thru White's 5th move.

Hate to break it to you, but this is "book", and main line for that matter, at minimum thru Black's 13th move!  After that, one could argue whether White's 14th move (14.Rf3) is book or not.  The "main line" that theory considers unclear is 14.Nc3 Qh1+ 15.Kxh1 Nxf2+ 16.Kg1 Nxd1 17.Nxd1 and it has an assessment of unclear.  There would really be no "book move" after this as the line basically ends here.

But Black's 5th move is a book move and the best move.  You can not trust chess.com's garbage tool for what they call book.

They even call 1.e4 c5 2.Nf3 e6 3.d3 Nc6 4.g3 g6 5.Bg2 Bg7 6.O-O the "Sicilian Defense, French Variation".  First off, there is no "French Variation", and secondly, it's the Kings Indian Attack (or KIA vs Sicilian).

Hopefully it has gotten thru your thick skin that it is time for you to invest in books (plural) if you want to seriously know and actually learn anything about chess openings and theory.

@ThrillerFan talks rudely.

No, I simply speak the truth and am blunt.  Being blunt about something, and being rude, are NOT the same thing.

Being rude would be like saying how dumb someone is to think something, or things of that nature!

Learn the difference between being rude and being blunt.  Two totally different things, and there is absolutely nothing wrong with being blunt!  The truth hurts sometimes.

Having been in check means nothing.  You simply cannot castle out of check, over check, or into check, and you cannot castle if you have moved the King, or if you have moved the Rook on the side you are castling.  I make absolutely no claim that the following is theory, or book, or even good moves.  I simply do it to illustrate the point in response to the post.

@ThrillerFan okay. I am surprised after your above comment "The concept of "Book Moves" on chess.com is utter garbage!" - Let some NM, CM, GM comment on the analysis tool. I know that the tool is following opening encyclopedia and that is all. I don't have five volumes of that. And thanks for your words.

The truth is, that tool is utter garbage comparatively speaking to more useful sources.  When it goes around saying that the "best move" is dubious, that's total garbage!  It doesn't even know it's a book move and the best move theoretically!

Not all bots are built the same.  Some are very weak, and when it comes to openings, many are very dependent on Opening Books (yes, they are separate programs that you have to load on your computer for a bot to correctly understand openings - just like endgame tablebases - with no tablebase, it will tell you that KRN vs KR with no immediate skewer or fork is "+3" when in reality, it's 0.00 (which with tablebases programmed in, it would figure out that it's 0.00).

An over the board Expert (which is what I am - one step below NM) can easily figure that out.  It doesn't take a GM to figure that out at all.  Again, simply being honest.  Might not be what you want to hear, but it's the sheer truth!

Also, most opening encyclopedias are outdated.  They haven't been published in 25 years.  You don't even want the 5 "volumes" of ECO.  Now-a-days, with computers, people need to know and understand openings deeper.  For example, after 1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.Nf3 O-O 6.Be2 e5 7.O-O, it is not enough to simply know that Black has 7...Nc6, 7...Na6, 7...Nbd7, 7...exd4, etc.  Each move has a different level of respect, and some are stronger (7...Nc6, 7...Na6) than others (7...exd4), but you need to understand the ideas behind each of them, not just claim it's a book move.  Specialized books on understanding the King's Indian Defense would be what you need if the King's Indian was of interest to you.  This would not mean an advanced repertoire, like Grandmaster Repertoire: The King's Indian volumes 1 thru 5.  No!  I'm more talking books that explain the King's Indian.  Ones like the following:

King's Indian Defense - Move by Move

King's Indian Warfare (Chapters are sorted by middlegame theme, not opening variation)

Opening Simulator: The King's Indian (This book is maybe 80 to 90 pages of theory, and then 400 or so problems from positions that specifically come from the King's Indian Defense).

Does it cost money?  Yes!  But you get what you pay for.  The tool here is extremely weak!  The bot here is very weak too!  I know that from playing correspondence games on a site that allows bots (ICCF), and you try to use the one here as a guide for your moves (I emphasize guide - just copying computer moves doesn't work in correspondence chess when playing the big guys - you will lose every time), you are behind the 8-ball.  Other programs are significantly stronger than what they use here!

Isn’t this line for Black called the Archangelsk or Neo-Archangelsk or something like that?