The vertical flow diagram presents identification, screening, eligibility, and inclusion stages. Records identified through Scopus are 39.274 and through Web of Science are 3.972, giving total records identified 43.246. After duplicate removal, records are 42.242. Records screened by title and abstract are 42.242, with 32.389 excluded for reasons including not focused on customer or consumer journey 25286, not focused on marketing intermediaries 6090, not peer reviewed journal articles 556, and not in English 457. Full text articles assessed for eligibility are 9853, with 9.817 excluded for reasons including intermediaries not in B 2 C context 547, only tangential mention of intermediaries 8914, and focus on distribution channels not purchase journey 356. The final inclusion shows 36 studies included in the systematic review.PRISMA flow diagram of systematic literature review process
Note: This flow diagram follows PRISMA guidelines. The search was conducted in April 2024 using Scopus and Web of Science. Following Hiebl (2021), we used a deliberate two-stage approach: Phase 1 searched for intermediary types (“marketing intermediar*” OR “surrogate consumer*” OR “opinion leader*” OR “influencer*” OR “expert source*” OR “supplier-affiliated intermediar*”); Phase 2 applied content-based screening to identify articles substantively addressing customer journey contexts (pre-purchase, purchase and post-purchase stages). This approach captured foundational studies using alternative terminology while ensuring all included articles address intermediary influence on customer journeys. Inclusion criteria: peer-reviewed journal articles in English; B2C contexts; and substantive analysis of intermediary influence on customer journey stages