Those are indeed cuts from a box. Called the "1969 NBAP Member" cards by PSA. Per PSA:
"The 1969 NBAP Members basketball set, once again, break from the norm and measure approximately 2-3/4” by 4-1/2”, though variations in size may appear. Each card features a black-and-white photo of the player in-action on the court, or posed before a blank background surrounded by a light blue border with the player’s name and N.B.A.P. member printed in black at the bottom. Because the cards don’t display the NBA logo, it is assumed that the league may not have sanctioned the set and the cards were potentially hand-cut from basketball shoeboxes such as Converse. These unnumbered, blank-backed cards may have been distributed in the early 1970s as it includes Kareem Abdul Jabbar, but also Bill Russell, who retired after the 1968-69 season. This relatively unattractive, but scarce 20-card set (though more may surface) is anchored by the likes of Hall of Famers Kareem Abdul Jabbar, Wilt Chamberlain, John Havlicek, Oscar Robertson, Bill Russell and Jerry West among others."
The Chamberlain is supposed to look like this:
They are pretty hard to find. The ones shown are really hacked up (no better than "A" grade) but still valuable. Last one looks like Len Wilkens.