Not only that, but the publisher also played into the era's growing popular fascination with the para- or supernatural,[3] which eventually culminated in the long-running and hugely successful 1993-2000 X-Files television series and the many motion picture emulators it spawned afterwards.

[4] The Enchanted World series had already set in motion Time-Life Books' trend towards more sensationalism away from the hitherto soberly and scientifically written publications, the publisher was until then renowned for.

Mysteries of the Unknown though, took it up a notch and the actual "The Editors of Time-Life Books" content writers/creators resented their management for it, or as Corry had put it, "Oh yeah.

On 16–17 August 1987 the Harmonic Convergence event took place which sparked a massive upsurge in worldwide interest in the topics covered by the Time-Life series, and sales took off with Corry recalling that "[r]ight after that, in the fall of '87, we couldn't print enough books."

Executed in hardcover, each volume was bound in black faux leatherette, the cover endowed in silver printed text imprints, and with a square shaped illustration glued on.

It resulted for the time being in a decided recovery of the company's overall book sales which went a long way to explain the long-lived availability of Mysteries of the Unknown series well into the late 1990s.

However, in 1997 a separate printing was commissioned by Barnes & Noble as retail exclusives for their bookstore chain, and while these were otherwise nearly indistinguishable from the main home market releases, safe for the copyright colophons, they were endowed with dust jackets.

An out-of-the-ordinary home market release concerned the Chinese-language versions Time-Life Books started to issue a year earlier in North America on behalf of the Chinese-speaking populace.

The Amsterdam subsidiary maintained administrative satellite offices in the UK, Germany and France which facilitated the series publication by Time-Life Books themselves.

[15] Hobby & Work was actually predominantly a partwork publisher, a publication format particularly popular in southern Europe at the time, and not only reissued the series in the original hardback book format, but had each book split up in five magazine-style paperback parts as well, concurrently selling them as magazine issues through the newsstand channel with one of them accompanied by a 30-minute VHS-tape that dealt with the underlying topic.

[16] As a matter of fact, this also applied to the Spanish edition as Folio co-published the series with specialized Madrid partwork publisher Ediciones del Prado who had already marketed the newsstand variant of the publication in a similar way two years before Hobby & Work would do.

Coined Mystikkens verden, the series saw a partial publication in Denmark and Norway,[18] as with their southern neighbors in a book format copied from the source material.

The second known Latin-American edition was the 1992-93 Misterios de lo desconocido Spanish-language publication released in Argentina by Editorial Atlántida S.A., a major magazine publisher from Buenos Aires.

The first concerned the 1999 second-edition German-language hardcovers without a dust jacket release, licensed to Eltville-based Predita Verlag who released these volumes under its "ECO Köln/VVA" imprint, featuring deviant cover art and newly assigned ISBNs, but did not carry the first edition Geheimnisse des Unbekannten series title though the original Time-Life cover illustration was printed on the back-cover.

Also executed as simple hardcovers with again new covers they were this time around issued with no ISBNs and subordinated under the publisher's "Weltbild-Sammler Editionen" collection, mentioning the original German series title as subtitle.

Titled "A collection from Mysteries of the Unknown" (OCLC 21492777, no ISBN issued), the in Prussian blue wrapped magazine-style book was just that, a sampling for prospective subscribers who were inquisitive about what the main series was all about, with its contents partially lifted from volumes 2 and 6.

In 2006, the excerpt book was reissued (ISBN 0760781095) by Barnes & Noble on behalf of their bookstore chain, again fully licensed by then-owner of Time-Life Books, Direct Holdings Americas Inc. Home market DTC sales started to slow down from 1991 onward and it was the subsequent year decided to stop adding new titles to the series in order to free up the editorial staff for new series projects.

These concerned deluxe facsimile faux-leather bound reproductions of eyewitness accounts written by people who had firsthand experience with any of the events covered in the main series or by experts on any of these matters.

[27] One year later subsidiary Time-Life Audiobooks reissued (part of) the series as taped audio cassette books in both English as well as Chinese (OCLC 818865412), with newly assigned ISBNs for each.

Conceived by the New York City-based Wunderman Worldwide agency and Time-Life's own Tom Corry, the ad campaign stood out for its vigor and longevity as it touted a plethora of variant commercials,[30][3] many of which currently featured on YouTube.

In addition, US customers who responded by telephone to the television ads were in 1990 rewarded with a free gift consisting of the "Psychic Powers" video tape, which was not included in the above-mentioned ten-tape series released five years later, and therefore remained an actual exclusive.