The Vairant Aasimar and Eladrin Elf are both sourced from the DMG and are available for free on DDB, because WoTC released a free preview of the DMG **
BUG: When you click on Variant Aasimar and then "Variant Aasimar Details Page", it take you to a page that says you need to buy Volo's. This is incorrect -- the Aasimar subraces that are unlocked with Volo's are Fallen, Scourge, and Protector. The Variant subrace is not in Volo's, only appears in the DMG and is not unlocked with a Volo's purchase.
BUG: Both of these races appear under the source "Players Handbook". These are not in the Players Handbook
BUG: Both of these subraces appear under the source "Basic Rules". They are not in the basic rules PDF
The Vairant Aasimar and Eladrin Elf are both sourced from the DMG and are available for free on DDB, because WoTC released a free preview of the DMG **
** The free DMG preview is hosted here: http://media.wizards.com/2014/downloads/dnd/DMG_286.pdf