求解：书籍的系列

luma

All 3 of those bos #7 are "official" bos-publications, but different editions. With new editions came new covers.
I have no idea in which order these 3 were published and the British Origami Society site doesn;t help here either. Moreover: they no longer have a #7 anymore :-)

https://www.britishorigami.org/wp-content/uploads/2021/10/Available_Folding_Catalogue_2021_v1.pdf

For me #7 probably is their most IMPORTANT publication as chess is anothe passion of mine ;-)