Chelsea have made Borussia Dortmund striker Pierre-Emerick Aubameyang their main summer transfer target, [football] direct news understands.A source close to Stamford Bridge told FDN the jet-heeled hitman has impressed club scouts, who have returned to the capital with glowing reports for boss Jose Mourinho and his technical staff.The Blues are desperate to add firepower to their squad when the transfer window reopens, with up to three strikers set to arrive before next season gets under way.Aubameyang’s pace and power have caught the eye in the Bundesliga and Chelsea are keen to wrap up a deal in the early weeks of the window, when veteran forward Samuel Eto’o set to depart on a free transfer.Fernando Torres and Demba Ba could also follow him out of the exit door as Mourinho rebuilds for the next campaign.Aubameyang has four years remaining on his contract with Dortmund, and Chelsea are well aware that they will have to come up with a significant sum of money to persuade the German outfit to part with the 24-year-old.