diff --git a/.gitignore b/.gitignore
index 6f9e0ec..a203027 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
 bin
 obj
+.idea
 *ReSharper*
 packages
 *.pyc
diff --git a/OAuth2/Client/IClient.cs b/OAuth2/Client/IClient.cs
index e4df633..f37f1c8 100644
--- a/OAuth2/Client/IClient.cs
+++ b/OAuth2/Client/IClient.cs
@@ -44,7 +44,7 @@ public interface IClient
         /// Callback request payload (parameters).
         /// <example>Request.QueryString</example>
         /// </param>
-        UserInfo GetUserInfo(NameValueCollection parameters);
+        UserInfo GetUserInfo(NameValueCollection parameters, NameValueCollection queryParameters = null);
 
         /// <summary>
         /// Client configuration object.
diff --git a/OAuth2/Client/Impl/FacebookClient.cs b/OAuth2/Client/Impl/FacebookClient.cs
index 6697905..45d23f1 100644
--- a/OAuth2/Client/Impl/FacebookClient.cs
+++ b/OAuth2/Client/Impl/FacebookClient.cs
@@ -71,7 +71,7 @@ protected override Endpoint UserInfoServiceEndpoint
         /// </summary>
         protected override void BeforeGetUserInfo(BeforeAfterRequestArgs args)
         {
-            args.Request.AddParameter("fields", "id,first_name,last_name,email,picture");
+            args.Request.AddParameter("fields", "id,first_name,last_name,email,picture.width(256).height(256)");
         }
 
         /// <summary>
@@ -81,7 +81,7 @@ protected override void BeforeGetUserInfo(BeforeAfterRequestArgs args)
         protected override UserInfo ParseUserInfo(string content)
         {
             var response = JObject.Parse(content);
-            const string avatarUriTemplate = "{0}?type={1}";
+            const string avatarUriTemplate = "{0}";
             var avatarUri = response["picture"]["data"]["url"].Value<string>();
             return new UserInfo
             {
@@ -91,9 +91,9 @@ protected override UserInfo ParseUserInfo(string content)
                 Email = response["email"].SafeGet(x => x.Value<string>()),
                 AvatarUri =
                 {
-                    Small = !string.IsNullOrWhiteSpace(avatarUri) ? string.Format(avatarUriTemplate, avatarUri, "small") : string.Empty,
-                    Normal = !string.IsNullOrWhiteSpace(avatarUri) ? string.Format(avatarUriTemplate, avatarUri, "normal") : string.Empty,
-                    Large = !string.IsNullOrWhiteSpace(avatarUri) ? string.Format(avatarUriTemplate, avatarUri, "large") : string.Empty
+                    Small = !string.IsNullOrWhiteSpace(avatarUri) ? string.Format(avatarUriTemplate, avatarUri) : string.Empty,
+                    Normal = !string.IsNullOrWhiteSpace(avatarUri) ? string.Format(avatarUriTemplate, avatarUri) : string.Empty,
+                    Large = !string.IsNullOrWhiteSpace(avatarUri) ? string.Format(avatarUriTemplate, avatarUri) : string.Empty
                 }
             };
         }
diff --git a/OAuth2/Client/Impl/TwitterClient.cs b/OAuth2/Client/Impl/TwitterClient.cs
index cdd2cfb..230be78 100644
--- a/OAuth2/Client/Impl/TwitterClient.cs
+++ b/OAuth2/Client/Impl/TwitterClient.cs
@@ -1,3 +1,4 @@
+using System;
 using Newtonsoft.Json.Linq;
 using OAuth2.Configuration;
 using OAuth2.Infrastructure;
@@ -109,14 +110,14 @@ protected override UserInfo ParseUserInfo(string content)
             return new UserInfo
             {
                 Id = response["id"].Value<string>(),
-                Email = null,
+                Email = response["email"] == null ? null : response["email"].Value<string>(),
                 FirstName = firstName,
                 LastName = lastName,
                 AvatarUri =
                     {
-                        Small = avatarUri.Replace("normal", "mini"),
-                        Normal = avatarUri,
-                        Large = avatarUri.Replace("normal", "bigger")
+                        Small = avatarUri,
+                        Normal = avatarUri.Replace("normal", "bigger"),
+                        Large = avatarUri.Replace("_normal", "")
                     }
             };
         }
diff --git a/OAuth2/Client/OAuth2Client.cs b/OAuth2/Client/OAuth2Client.cs
index 134d47a..7e26cc8 100644
--- a/OAuth2/Client/OAuth2Client.cs
+++ b/OAuth2/Client/OAuth2Client.cs
@@ -41,7 +41,7 @@ public abstract class OAuth2Client : IClient
         /// <summary>
         /// Access token returned by provider. Can be used for further calls of provider API.
         /// </summary>
-        public string AccessToken { get; private set; }
+        public string AccessToken { get; set; }
 
         /// <summary>
         /// Refresh token returned by provider. Can be used for further calls of provider API.
@@ -110,11 +110,19 @@ public virtual string GetLoginLinkUri(string state = null)
         /// Obtains user information using OAuth2 service and data provided via callback request.
         /// </summary>
         /// <param name="parameters">Callback request payload (parameters).</param>
-        public UserInfo GetUserInfo(NameValueCollection parameters)
+        /// <param name="queryParameters">Callback request payload (query parameters).</param>
+        public UserInfo GetUserInfo(NameValueCollection parameters, NameValueCollection queryParameters = null)
         {
-            GrantType = "authorization_code";
-            CheckErrorAndSetState(parameters);
-            QueryAccessToken(parameters);
+            queryParameters = queryParameters ?? new NameValueCollection();
+            
+            if (this.AccessToken == null)
+            {
+                GrantType = "authorization_code";
+                CheckErrorAndSetState(parameters);
+                
+                QueryAccessToken(parameters);
+            }
+
             return GetUserInfo();
         }
 
@@ -126,7 +134,10 @@ public string GetToken(NameValueCollection parameters)
         {
             GrantType = "authorization_code";
             CheckErrorAndSetState(parameters);
-            QueryAccessToken(parameters);
+            
+            if (this.AccessToken == null)
+                QueryAccessToken(parameters);
+            
             return AccessToken;
         }
 
diff --git a/OAuth2/Client/OAuthClient.cs b/OAuth2/Client/OAuthClient.cs
index 909fe4b..6bb115a 100644
--- a/OAuth2/Client/OAuthClient.cs
+++ b/OAuth2/Client/OAuthClient.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Specialized;
+using System.Runtime.InteropServices.ComTypes;
 using System.Web;
 using OAuth2.Configuration;
 using OAuth2.Infrastructure;
@@ -38,12 +39,12 @@ public abstract class OAuthClient : IClient
         /// <summary>
         /// Access token received from service. Can be used for further service API calls.
         /// </summary>
-        public string AccessToken { get; private set; }
+        public string AccessToken { get; set; }
 
         /// <summary>
         /// Access token secret received from service. Can be used for further service API calls.
         /// </summary>
-        public string AccessTokenSecret { get; private set; }
+        public string AccessTokenSecret { get; set; }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="OAuthClient" /> class.
@@ -78,13 +79,20 @@ public string GetLoginLinkUri(string state = null)
         /// </summary>
         /// <param name="parameters">Callback request payload (parameters).
         /// <example>Request.QueryString</example></param>
+        /// <param name="queryParameters">Callback request payload for query user info (parameters).
+        /// <example>Request.QueryString</example></param>
         /// <returns></returns>
-        public UserInfo GetUserInfo(NameValueCollection parameters)
+        public UserInfo GetUserInfo(NameValueCollection parameters, NameValueCollection queryParameters = null)
         {
-            AccessToken = parameters.GetOrThrowUnexpectedResponse(OAuthTokenKey);
-            QueryAccessToken(parameters.GetOrThrowUnexpectedResponse("oauth_verifier"));
+            queryParameters = queryParameters ?? new NameValueCollection();
+            
+            if (this.AccessToken == null || this.AccessTokenSecret == null)
+            {
+                AccessToken = parameters.GetOrThrowUnexpectedResponse(OAuthTokenKey);
+                QueryAccessToken(parameters.GetOrThrowUnexpectedResponse("oauth_verifier"));
+            }
 
-            var result = ParseUserInfo(QueryUserInfo());
+            var result = ParseUserInfo(QueryUserInfo(queryParameters));
             result.ProviderName = Name;
 
             return result;
@@ -207,7 +215,7 @@ protected virtual void BeforeGetUserInfo(BeforeAfterRequestArgs args)
         /// <summary>
         /// Queries user info using corresponding service and data received by access token request.
         /// </summary>
-        private string QueryUserInfo()
+        private string QueryUserInfo(NameValueCollection queryParameters)
         {
             var client = _factory.CreateClient(UserInfoServiceEndpoint);
             client.Authenticator = OAuth1Authenticator.ForProtectedResource(
@@ -215,6 +223,11 @@ private string QueryUserInfo()
 
             var request = _factory.CreateRequest(UserInfoServiceEndpoint);
 
+            foreach(var parameter in queryParameters.AllKeys)
+            {
+                request.AddParameter(parameter, queryParameters[parameter]);
+            }
+
             BeforeGetUserInfo(new BeforeAfterRequestArgs
             {
                 Client = client,