of which. in which, or with which Whereas, in accordance with the implementation of the Agreement and in connection with the Article 25.2.1 of the Agreement regarding Addition and Revision, ABC corporation through its letter no. 0xxx/EPI.01.02/xxx/2018 dated xx May 2018 has requested DEF corporation to add scope of the Agreement to fulfill demand of Gas supply in carrying out performance test at several DEF corporation’s machine gas Power Plants in Jayapura, Nabire, Ternate, Kendari, Flores (in which/ at which/ of which/ with which/ others?) the performance test shall be conducted before guarantee period of Gas Machine Power Plant ends. This is very confusing for non-native speaker to choose in which, at which, of which or others.