@jpgr&b what leisure books have done is appended the cover price in cents to the isbn (isbn10 by default) - a common trick by some (many) merkin mmpb publishers for quite a while.
they - nordon industries/publications, leisure books - also went through a period of inventing fake isbns by taking their legitimate publisher code, 0-8439-, adding the previous three-digit numerical part of the cat#, and then interpolating however many zeroes it took to expand the result up to ten digits, the final digit being the final digit of the previous cat# instead of a checksum digit (before appending the cover price in cents, giving a thirteen digit-long number-string). . .
these are almost invariably detectable if you bother to recalculate what the checksum digit should have been, comparing this with what they claim: they can only match through sheer chance/chancer's luck.
in this particular case, the isbn appears to be legitimate - they did get over the faking period - and
the cat# on the cover is 1000 - top fly (right-hand) corner, under the lllogo & ''leisure''.
n.b. ''1st january'' day and month of publication year if taken from amazon is not reliable without support from publisher's promotional material, laid-in review copy slip, dated reviews from newspapers & magazines around the date of a book's first publication, and similar;
amazon inputs these merely to fill the day & month fields with something. . .