Google API Where() 和 When() 命名空间

我想知道要向我的项目添加什么（导入？参考？）以便能够为Google日历使用Where（）- 和When（）-方法。

法典：

Where eventLocation = new Where();
eventLocation.ValueString = "South Tennis Courts";
entry.Locations.Add(eventLocation);
When eventTime = new When(DateTime.Now, DateTime.Now.AddHours(2));
entry.Times.Add(eventTime);

错误：

Error 1 The type or namespace name 'Where' could not be found (are you missing a using directive or an assembly reference?)
Error 3 The type or namespace name 'When' could not be found (are you missing a using directive or an assembly reference?)  

更新：当前进口：

using Google.GData.Client;
using Google.GData.Calendar;
using Google.GData.Extensions;
using Google.GData.AccessControl;