Spain Volume 14 (85.013)
There is no hard proof of volume 14 having been issued in Spain, but there is good circumstantial evidence: each time a Spanish release appeared, the music paper El Mundo de los Discos (which translates as "World of Records" or "Record World" in English) gave it a notice, usually some months after the release.
The image above shows their report on a Spanish record numbered 85.013-V (and a translation into English). Since the confirmed volume 15 is numbered later than this, and this is the prior notice in the paper, it is reasonable to assume this is for volume 14 (although it could conceivably be for volume 13).
This paper is dated 22 May 1971 for an album which in the UK had appeared before Christmas!
Further info on this record is being sought.