(the long deteriorated cover of my copy of Mobile Suit Gundam Trump Cards For Children, published during the earliest annals of Mobile Suit Gundam's broadcast, if not even prior.)
These cards feature very unique early interpretations of the Zabi family, primarily with the depiction of Kycilia Zabi - with her stance, her wide legs are not original to Yasuhiko's original concept art at any stage. I ran across this art as far back as 2017 or so and even made a drawing based on it, though I never knew how to acquire these cards back then. With that said, we could always compare the latter with Yasuhiko's two main depictions of Kycilia, one at the mid to late 1978 stage for Freedom Fighter Gunboy and then the latter version used for the duration of 0079.
The other cards in this set are a regular printed suite of cards with the same art used on any other, whereas Amuro from the box cover is shown on the back. The lithograph used appears to be from the Poppy books as well, though I have never seen it in any early magazine or text prior. Based on these designs and printing, I would guess that this set is from early 1979.
Sunrise's earliest design choices for these books, notepads and more relied on an aesthetic already championed for the children's market at the time, not making a genuine foray into the teenage and early 20s market until post 1980. Early depictions of these day-glo colored prints and cel paintings can be seen in TV Magazine. First published in 1971 by Kodansha, the April 1979 issue up until the January 1980 issue give information about Gundam. However, early depictions could only rely on these images as Gundam hadn't even begun broadcasting yet:
(Some of the earliest concept art shown was illustrated by Futoshi Okazaki (岡崎甫雄) , Ichiro Sekiguchi (関口猪一 郎) and Tanaka Manami (田中愛望). Taken from the Mobile Suit Gundam Memorial Blu-Ray Boxset released in 2013.)
(Examples of Futoshi Okazaki (岡崎甫雄)'s later illustrations for Zeta Gundam, which make a grand departure visually and aesthetically by the mid 1980s vs his work for Gundam's original broadcast promo materials.)
Many of these summarize early events that would be shown in Gundam before the broadcast and include early logos that would never be used again. It summarizes aspects of Side 7's importance, the Gundam's strength, White Base, etc. A unique point mentioned is that the enemy, Zeon, are deemed as aliens, which ties into Gunboy lore. Early depictions of the beam saber are yellow whereas the Gundam Hammer uses the "heat hammer'' settei. Also included was an unused weapon, a large gun that nearly mirrors that of the M120A1, or the "Zaku Machine Gun".
There isn't any other unique art present on these cards as I initially thought, sans for this depiction of Degwin Sodo Zabi, though this image in particular had already been in mass circulation and never truly deviated from Yasuhiko's original concept artwork or setting documents - if anything, it's just a xerox. At this stage, I find it interesting that Kycilia and Degwin were used as the villains for the joker cards from a design choice perspective. I have other materials like so and will be sharing them in mind!
(JOKER - For Children. Mobile Suit Gundam, copyright Sotsu Agency/Nippon Sunrise. This depiction of Kycilia Zabi is unique to the cards themselves and was never used again on record. This is a unique example of early Gundam concept art being changed to fit the demand for children's products at the time, and many of these concepts were recycled, this being an exception.)
