While there are other topics that I’d rather be discussing, given the sudden popularity of this phrase outside of far‐right circles I think that it’s too important to overlook now.

Quoting Grzegorz Rossoliński-Liebe’s Stepan Bandera: The Life and Afterlife of a Ukrainian Nationalist, page 179:

[T]he OUN-B employed the fascist salute of raising the right arm “slightly to the right, slightly above the peak of the head” while calling “Glory to Ukraine!” (Slava Ukraïni!), the response to which was “Glory to the Heroes!”

Page 70:

Among the organizations whose members went over to the OUN was the League of Ukrainian Fascists (Soiuz ukraïns’kykh fashystiv, SUF), which invented the fascist greeting “Glory to Ukraine!” (Slava Ukraïni!).

(This merger probably occurred in either 1929 or the early 1930s.)

Pages 128 (for context) and 139:

In a trial lasting from 18 November 1935 to 13 January 1936, twelve OUN members—Stepan Bandera, Daria Hnatkivs’ka, Iaroslav Karpynets’, Ievhen Kachmars’kyi, Mykola Klymyshyn, Mykola Lebed’, Ivan Maliutsa, Bohdan Pidhainyi, Roman Myhal’, Iaroslav Rak, Iakiv Chornii, and Kateryna Zaryts’ka—were accused either of organizing and conducting the assassination of [Polish interior minister Bronisław Wilhelm] Pieracki, or of helping the assassin to escape. In addition, all of them were accused of “being active in the OUN, which tried to separate from the Polish state its south-eastern voivodeships.”

[…]

The most spectacular witness that day was the young OUN member Vira Svientsits’ka. As many other OUN witnesses before her had done, she informed the court in Ukrainian that she spoke Polish but was prepared to testify only in Ukrainian. For this statement, the chairman punished her with a fine of 200 złotys or ten days imprisonment and ordered the guards to lead her out. As Svientsits’ka was passing the dock, she went toward the defendants, raised her right arm, and shouted, “Slava Ukraïni!” The defendant Karpynets’ stood up, raised his arm, and answered, “Slava Ukraïni!” This is apparently the first recorded fascist salute that OUN members performed in public.

Page 148:

After the chairman finished reading the verdict, Bandera and Lebed’ stood up, raised their right arms slightly to the right, just above their heads—as they had learned from Italian and other fascists—and called out “Slava Ukraïni!” For this gesture, which interrupted the final moments of the proceedings, both young men were removed from the courtroom.

Pages 151–3:

Klymyshyn wrote in his memoirs that, toward the end of the proceedings when the defendants were allowed to have their last say, Bandera shouted: “Iron and blood will decide between us,” and all defendants called “Slava Ukraïni!” […] The last defendant to enter the courtroom, shortly before the trial began, was Bandera. As he entered, he performed a fascist salute, raising his right arm and shouting “Slava!” or “Slava Ukraïni!” All the defendants in the courtroom answered him in the same manner. […] Close to the exit, Stets’ko turned back to the public, raised his right arm, and called out, “Slava Ukraïni!” The prosecutor said that this was the third time that a defendant had performed a demonstrative act, and that he was requesting that journalists and other observers be removed from the courtroom.

Page 156:

The problem of fascist greetings in the courtroom appeared again on 16 June 1936, the sixteenth day of the trial, when some OUN members were called as witnesses. The first was Lebed’, who naturally did not admit belonging to the OUN. Leaving the courtroom, he raised his right arm toward the defendants and called out, “Slava Ukraïni!” Stets’ko and Ianiv answered him with the same fascist salute. The next one was Lemyk, Mailov’s assassin. When Lemyk had finished testifying and was leaving the courtroom, he greeted the other defendants with the raised arm and the words “Slava Ukraïni!” The last witness on this day was Oleksandr Kuts. After Kuts used the same Ukrainian fascist salute as Lebed’ and Lemyk before him, the prosecutor again proposed that the trial be closed to the public, but the court rejected his application. References to the fascist greetings were again deleted by the censorship from the newspaper reports.

Page 444:

Describing the trial of the OUN in Warsaw in 1935–1936, Mirchuk changed the political meaning of the fascist salute “Slava Ukraïni!” which the OUN members performed several times in the courtroom. He described how the OUN members shouted “Slava Ukraïni!” but did not mention that they extended their right arms. He thereby turned this greeting into something for which Ukrainian patriots born after the Second World War could have sympathy.

Page 198:

When the [Fascist] Germans and Ukrainian nationalists entered Lviv on 30 June, there were 160,000 Jews in the city, 140,000 Poles, and 70,000 Ukrainians. The number of Jews in Lviv had increased significantly after the beginning of Operation Barbarossa, as Jewish refuges escaped from the territories of the Second Republic occupied by [the Axis], to those occupied by the Soviet Union. Among the [Axis] units entering the city was the Ukrainian Nachtigall battalion, which formed part of the 1st. Battalion of the special command regiment Brandenburg 800. When they marched into Lviv, the soldiers of this battalion shouted “Slava Ukraïni!” to the local people who welcomed them enthusiastically. Ukrainians in Lviv were very excited at the sight of the Ukrainians in [Fascist] uniform.

Pages 255–6:

In early 1943, Himmler ordered the establishment of a Waffen-SS Galizien division, made up of Ukrainian soldiers, but forbade it to be called Ukrainian. […] Vasyl’ Veryha, a veteran of this division, mentioned in his memoirs that Ukrainian policemen greeted the Waffen-SS Galizien soldiers with “Heil Hitler!” and that the response was “Glory to Ukraine!” (Slava Ukraïni!).

(Emphasis added in all cases.)