Dear organizing committee, I am addressing you with this email regarding the registration to the DRUID conference for the authors of the papers with id numbers 6110 and 6114. We are obliged to receive the invoices of our registration payments under the *name* and *VAT number* *of our institution* in order for them to be fully refunded. To our understanding, if we implement the standard procedure via our DRUID profiles, the invoices will be delivered as a personal receipt. As a result, we present you with *a request to issue our invoices under our institutional details* and provide us with *guidelines regarding the proper actions that need to be implemented in the online payment procedure*. The names of the participants are: Aggelos Tsakanikas, atsaka@central.ntua.gr Petros Dimas, petros.dimas92@gmail.com Dimitrios Stamopoulos, dstamopoulos@mail.ntua.gr The institutional details are: Name: N.T.U.A. RESEARCH COMMITTEE Invoice details: PATISION 42, 10682 ATHENS, GREECE VAT No.: EL099793475 With kind regards, On behalf of the co-authors of the papers, Petros Dimas -- Petros Dimas Chemical Engineer | MSc in Applied Economics and Financial Analysis PhD Candidate | Researcher Laboratory of Industrial & Energy Economics (http://liee.ntua.gr/) National Technical University of Athens Zografou Campus, Athens 15780 Tel. +30 2107723283 E-mail: petros.dimas92@gmail.com ; petros_dimas92@outlook.com Office: H.404 (Level 4, Compartment H)