In the case provided for in Article 53(5)(b), the International Bureau shall communicate the decisions of the Assembly (other than those concerning the Assembly's own procedure) to the Contracting States which were not represented and shall invite them to express in writing their vote or abstention within a period of three months from the date of the communication. If, at the expiration of that period, the number of Contracting States having thus expressed their vote or abstention attains the number of Contracting States which was lacking for attaining the quorum in the session itself, such decisions shall take effect provided that at the same time the required majority still obtains.