ἐπειδήπερ
From LSJ
English (Strong)
from ἐπειδή and περ; since indeed (of cause): forasmuch.
English (Thayer)
(ἐπειδή περ Lachmann), conjunction (from ἐπεί, δή and περ), seeing that, forasmuch as; Itala and Vulg. quoniam quidem, since now (cf. Winer's Grammar, 448 (417)): Aristotle, phys. 8,5 (p. 256b, 25); Dionysius Halicarnassus 2,72; Philo ad Gai. § 25, and Attic writings from Thucydides down.)
Russian (Dvoretsky)
ἐπειδήπερ: conj. тж. раздельно так как, ведь NT.