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Sign "Только наличный расчёт": "Cash only"
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So, it's an Ace Combat universe?
Trivia time: In reality blatnoi is not an organization but a highest caste in Russian criminal hierarchy. It's a substantive noun, and as such it's subjected to inflection rules. So, correct usage would have been "blatnye" instead of "blatnoi guys".
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Newspaper "...ОС ГАЗЕТА": probably "РОС ГАЗЕТА" - "RUS NEWSPAPER"
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Sign in the front "ДЗ...": no idea
Sign in the back "Проте...": could mean a few things, my guess is "Протезы" - "Prostheses".
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I find it funny how author keeps using "Ч" instead of "Ц" in Muromets' name, yet makes distinction between "Ш" и "Щ" in a story.
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Handwritten note "Мишень": Literally "shooting target". "Цель" (simply "target"), would've been a better choice of a word.