Trade Accounts Payable (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Trade Accounts Payable

At December 31 this account comprises:

	2016		2017
Unbilled services received		924,025		132,513
Invoices payable		350,559		1,250,586
Notes payable		2,033		69,947
		1,276,617		1,453,046