One of the most popular series of modules for Advanced D&D, based in the world of the Dark Elves.  The second trilogy in the GDQ series (comprised of the Giants, Drow, and Queen subseries).

D1 Descent Into the Depths of the Earth by Gary Gygax
D1-2 Descent into the Depths of the Earth by Gary Gygax
D2 Shrine of the Kuo-Toa by Gary Gygax
D3 Vault of the Drow by Gary Gygax

These modules were created as part of the over-arching story begun in G1 Steading of the Hill Giant Chief and concluded in Q1 Queen of the Demonweb Pits.  The entire series was finally compiled into supermodule GDQ1-7 Queen of the Spiders.

Originally produced as three separate monochrome modules, D1 and D2 were eventually combined into the color-covered D1-2 Descent into the Depths of the Earth.  The monochrome D3 was transferred directly into the color D3 Vault of the Drow.

D1-2 Descent into the Depths of the Earth comes with a double cover (module booklet nested inside two covers of maps).  Thanks to Eric Pass for this info. 

Interesting piece of trivia: on the cover page of the D1-2 module booklet, the Willingham ink sketch (of four drow) shows a small chest, and within that chest appears to be Captain America's shield and Iron Man's helmet!  The chest itself even shows Spider Man's mask.  According to contributor Pat Wilshire, such "Easter eggs" are often found in TSR art, and the influence of comic books on fantasy illustrators was often significant.  The artwork is not found in either of the D1 or D2 separate modules.  Thanks to Robert Jay for first noticing this, and to James Maliszewski for assistance.

Printing Information

D1 Descent Into the Depths of the Earth

• First (1978):  Monochrome.  Wizard logo, centered on bottom.  No ISBN, no indication of printing #, no starburst on front cover bottom right.  (Thanks to Scott Cordiner for the scan).
  

• Second (Dec 1978):  Monochrome.  Wizard logo is offset from a starburst stating "Official D&D Tournament Module used at GenCon XI".  No ISBN.  Bottom of front cover states "2nd Printing, December 1978".  Some illustration that were present in the First print are now missing: the giant slug on pg 3, the pack lizard and drow on pg 5, the mind flayer on pg 7, the bugbears on pg 10, and the jermlaine on pg 12!  (Thanks to Michael Deaton for this info).  Strangely, we've heard of at least two Second print copies that do not have these missing illustrations, indicating that this error was caught and corrected copies were issued (thanks to Mike Badolato for this info).
  

• Third (Dec 1979):  Monochrome.  Wizard logo with starburst.  No ISBN.  Bottom of front cover states "3rd Printing, December 1979".  The missing illustrations from the Second print have now been re-included.
  

• Fourth (1980):  Monochrome.  Wizard logo with starburst.  ISBN is on back cover bottom left.  No printing notice. (Thanks to Michael Deaton, John Kozol, and Adrian Newman for this info).
  

• Fifth:  Monochrome.  Wizard logo with starburst.  ISBN is on front cover bottom left and back cover bottom right.  No printing notice.
  
  

• First (1981):  Color cover.  TSR Face logo.  ISBN on back cover bottom right.  (Thanks to Michael Deaton for the scan).
  

• Second:  Color cover.  TSR Face logo.  ISBN on back cover bottom right, Piece Code (116-F-9059) on back cover bottom left.
  

• Third:  Color cover.  TSR Face logo.  ISBN and Product Number on back cover bottom right, no Piece Code.
  

• Fourth:  Color cover.  TSR Face logo.  ISBN and Product Number on back cover bottom right, Piece code back cover bottom left.
  

• Fifth:  Color cover.  TSR Face logo.  Has an orange cardboard header glued to the top backside of the shrinkwrap, with the D&D logo and some other advertising.  This print was distributed to large retailers (such as Toys 'R' Us) and was designed to be hung on a rack.  This print is significantly rarer than earlier prints; we suspect the module itself, separate from the header, is actually a Fourth print, but confirmation on this is needed.  Further info on header modules is here.
  
  

D2 Shrine of the Kuo-Toa

• First (1978):  Monochrome.  Wizard logo, centered on bottom.  No ISBN.  No indication of printing #.  (Thanks to Scott Cordiner for the scan).
  

• Second (Dec 1978):  Monochrome.  Wizard logo is offset from a starburst stating "Official D&D Tournament Module used at GenCon XI".  No ISBN.  Bottom of front cover states "2nd Printing, December 1978".
  

• Third (Dec 1979):  Monochrome.  Wizard logo with starburst.  ISBN on the front cover, bottom left.  Bottom of front cover states "3rd Printing, December 1979".  (Thanks to Alain Bennett and Michael Deaton for help with this info).
  

• Fourth (1980):  Monochrome.  Wizard logo with starburst.  ISBN is on back cover bottom right (although some copies have been reported with the ISBN on the front cover bottom left instead; we don't know which version came first).  No printing notice.  (Thanks to John Kozol and Eric Pass for this info).
  

• Fifth:  Monochrome.  Wizard logo with starburst.  ISBN is on front cover bottom left and back cover bottom right.  No printing notice.
  
  

D3 Vault of the Drow

• First (1978):  Monochrome.  Wizard logo, centered on bottom.  No ISBN.  No indication of printing # (thanks to David Leverich for the scan).
  

• Second (Dec 1978):  Monochrome.  Wizard logo is offset from a starburst stating "Official D&D Tournament Module used at GenCon XI".  No ISBN.  Bottom of front cover states "2nd Printing, December 1978".
  

• Third (Dec 1979):  Monochrome.  Wizard logo with starburst.  ISBN on the front cover, bottom left.  Bottom of front cover states "3rd Printing, December 1979".  (Thanks to Josh Berling and Michael Deaton for help with this info).
  

• Fourth (1980):  Monochrome.  Wizard logo with starburst.  ISBN on back cover bottom right (although some copies have been reported with the ISBN on the back cover bottom left instead; we don't know which version came first).  No printing notice.  (Thanks to John Kozol and Chris Hoffner for this info).
  

• Fifth:  Monochrome.  Wizard logo with starburst.  ISBN on front cover bottom left and back cover bottom right.  No printing notice.
  

• Sixth:  Color cover.  TSR Face logo.  ISBN on back cover bottom left.  Some minor layout changes and additions to this print: a small web illustration on page 2 has been added (replacing a paragraph referencing modules G3 and D2 for background on Svirfneblin), the mountain/passage illustration on page 10 was previously divided over two pages in the monochrome version, a full-page illustration of Lolth on page 20 was inserted, and an illustration and description of Svirfneblin was added to the end.  Thanks to Rene Hurka for this info.
  

• Seventh:  Color cover.  TSR Face logo.  ISBN and Product Number on back cover bottom left.
  
  

The D-series modules have remained one of the most popular series TSR produced.  Values somewhat reflect the demand, rather than the abundant supply.

• D1 Descent into the Depths of the Earth (mono)
• D1-2 Descent into the Depths of the Earth (color)
• D2 Shrine of the Kuo-Toa
• D3 Vault of the Drow (mono)
• D3 Vault of the Drow (color)