Abrosov had access to archival materials - in particular, reports from Soviet air squadrons - on which it is possible to judge Soviet losses, but he still takes into account other sources (in particular - Spanish and German), on which he evaluates the losses of the Republicans (except the Soviet ones) and their opponents. How well he knows Spanish sources - I can't judge. But the book left a good impression.
Losses in July-August 1938 according to Abrosov:
- August 1st: 19:20 25 I-16s against 15 Bf.109s and 22 CR.32/He.51s, Republican losses - two I-16s, pilot Vicente Beltran Rodrigo parachuted out, Nationalist losses - one CR.32 (pilot Enrique Munaiz de Brea, KIA) and 1 He.51 (pilot name was not specified), in addition Horst Tietzen from 3.J/88 made an emergency landing.
- August 2nd: 3 I-16s were suddenly attacked by 20 Bf.109s, one I-16 returned to the airfield, two I-16s made an emergency landing on their territory; one Republican seaplane made an emergency landing on water, the crew was rescued.
- August 3rd, 3 I-16s were lost when returning after an SB escort to the Gandesa area, the reason was an unsuccessful landing at their airfield, two aircraft were written off, one was repaired, pilots Zyuzin, Glushkov and Zhuravlyov survived.
- August 5th, three air battles, Italians recognized the loss of one pilot (Luigi Ricci), in a crash, but most likely this crash was a consequence of the air battle; Soviet pilots had no losses, but two I-16s were crashed on landing (pilots Bykovsky and Zhuravlev, the planes were written off), one pilot made an emergency landing (Konovalov), the reason in all cases was insufficient control over fuel consumption and undisciplined pilots.
- August 9th, one I-16 crashed during the flight of Gritsevets's squadron to the front airfield, pilot Maksimenkov survived, the plane was written off, two planes collided while taxiing on the ground - minor repairs needed.
- August 12th, two SBs were shot down, one pilot was killed, the rest escaped by parachute, one I-16 (pilot Konovalov) separated from the formation and was fired by O.Bertram from 1.J/88. Konovalov's plane sustained a lot of damage and Konovalov himself was wounded, but he managed to land at his airfield. One I-15 was shot down on the Extremadura Front.
- August 13th, pilot Shaulov crashed his I-16 on landing, no information on the pilot's fate, but he was probably not injured.
- August 14th, two consecutive air battles with a total duration of about one hour, one I-16 made an emergency landing because of engine damage by He.111 gunners (pilot Kakutich received only bruises), two I-16s (pilots Glushkov and Fomin) suffered engine failures and landed at Reus airfield; pilot Lukovnikov on an I-16 collided with a CR.32 in a frontal attack, but at the last moment the CR.32 pilot went down, Lukovnikov's plane cut off the tail of the CR.32 with its propeller, then managed to return to his airfield.
- August 15th, one I-15 was shot down, the lightly wounded pilot escaped by parachute; pilot Pavlov's I-16 belly landed at Vendrel airfield because of battle damage, the pilot was not injured; pilot Turov's I-16 nosed over on landing, the pilot claimed to have been wounded before landing and the aircraft damaged by AA fire.
- August 18th, pilot Glushkov was ferrying a repaired I-16 but forgot to release the landing gear when landing, the belly landed plane could be repaired.
- August 19th, the Republicans lost three I-16s: one with Soviet pilot Vorob'yov and two with Spanish pilots (the names are not given), another I-16 of pilot Gerasimov was damaged, but landed at his airfield.
- August 20th, a rare case of a match - one I-16 (the Spanish pilot's surname is not specified) was missing, another I-16 pilot was wounded but landed at his airfield.
- August 23rd, also a match: pilot Pavlov was killed in an emergency landing by smashing his head on the sight of an I-16, pilot Volkov's I-16 belly landed at his airfield, pilot Maksimenkov's I-16 was shot down by anti-aircraft artillery in pursuit of a CR.32 - Maksimenkov parachuted out and was unharmed; another I-16 was shot down - according to some sources the pilot parachuted out, according to others he made an emergency landing, after which the plane burned out, the name of the Spanish pilot is not given; the Italians admit the loss of three CR.32s (Aldo Bracco was killed, Carlo Bonifaci was captured, Pió Tomaselli made an emergency landing).
- August 24th, an SB (crew commander Velichko) and two I-16s (both piloted by Spanish pilots, names were not specified) were shot down, one pilot MIA, the other escaped by parachute; pilot Boguslavchik's I-16 suffered combat damage to its landing gear and belly landed on its airfield; at least two CR.32s were shot down, pilots Arrechea Belzunce and Chapaprieta Inglado were captured.
- August 25th, no Republican aircraft losses were recorded; CR.32 "3-63" was shot down, pilot Jose M. Etayo Elizondo was killed.
- August 26th, two I-15s collided during an air battle, the pilots (names withheld) escaped by parachute.
- July 27th, a match - Abrosov mentioned two Grumman-type planes which did not return from the mission.
- September 2nd, one Delfín downed by AA fire. - According to Abrosov it happened on September 3rd.