diff --git a/bot.go b/bot.go
index 8154208..2ff6fa2 100644
--- a/bot.go
+++ b/bot.go
@@ -705,12 +705,13 @@ func (bot *BotAPI) GetGameHighScores(config GetGameHighScoresConfig) ([]GameHigh
 	return highScores, err
 }
 
+// AnswerShippingQuery allows you to reply to Update with shipping_query parameter.
 func (bot *BotAPI) AnswerShippingQuery(config ShippingConfig) (APIResponse, error) {
 	v := url.Values{}
 
 	v.Add("shipping_query_id", config.ShippingQueryID)
-	v.Add("ok", strconv.FormatBool(config.Ok))
-	if config.Ok == true {
+	v.Add("ok", strconv.FormatBool(config.OK))
+	if config.OK == true {
 		data, err := json.Marshal(config.ShippingOptions)
 		if err != nil {
 			return APIResponse{}, err
@@ -725,12 +726,13 @@ func (bot *BotAPI) AnswerShippingQuery(config ShippingConfig) (APIResponse, erro
 	return bot.MakeRequest("answerShippingQuery", v)
 }
 
+// AnswerPreCheckoutQuery allows you to reply to Update with pre_checkout_query.
 func (bot *BotAPI) AnswerPreCheckoutQuery(config PreCheckoutConfig) (APIResponse, error) {
 	v := url.Values{}
 
 	v.Add("pre_checkout_query_id", config.PreCheckoutQueryID)
-	v.Add("ok", strconv.FormatBool(config.Ok))
-	if config.Ok != true {
+	v.Add("ok", strconv.FormatBool(config.OK))
+	if config.OK != true {
 		v.Add("error", config.ErrorMessage)
 	}
 
diff --git a/configs.go b/configs.go
index cabae9a..5f3f259 100644
--- a/configs.go
+++ b/configs.go
@@ -900,6 +900,7 @@ type ChatConfigWithUser struct {
 	UserID             int
 }
 
+// InvoiceConfig contains information for sendInvoice request.
 type InvoiceConfig struct {
 	BaseChat
 	Title               string          // required
@@ -909,7 +910,7 @@ type InvoiceConfig struct {
 	StartParameter      string          // required
 	Currency            string          // required
 	Prices              *[]LabeledPrice // required
-	PhotoUrl            string
+	PhotoURL            string
 	PhotoSize           int
 	PhotoWidth          int
 	PhotoHeight         int
@@ -936,8 +937,8 @@ func (config InvoiceConfig) values() (url.Values, error) {
 		return v, err
 	}
 	v.Add("prices", string(data))
-	if config.PhotoUrl != "" {
-		v.Add("photo_url", config.PhotoUrl)
+	if config.PhotoURL != "" {
+		v.Add("photo_url", config.PhotoURL)
 	}
 	if config.PhotoSize != 0 {
 		v.Add("photo_size", strconv.Itoa(config.PhotoSize))
@@ -971,15 +972,17 @@ func (config InvoiceConfig) method() string {
 	return "sendInvoice"
 }
 
+// ShippingConfig contains information for answerShippingQuery request.
 type ShippingConfig struct {
 	ShippingQueryID string // required
-	Ok              bool   // required
+	OK              bool   // required
 	ShippingOptions *[]ShippingOption
 	ErrorMessage    string
 }
 
+// PreCheckoutConfig conatins information for answerPreCheckoutQuery request.
 type PreCheckoutConfig struct {
 	PreCheckoutQueryID string // required
-	Ok                 bool   // required
+	OK                 bool   // required
 	ErrorMessage       string
 }
diff --git a/helpers.go b/helpers.go
index 03467b1..132d957 100644
--- a/helpers.go
+++ b/helpers.go
@@ -641,23 +641,15 @@ func NewCallbackWithAlert(id, text string) CallbackConfig {
 	}
 }
 
-func NewInvoice(chatID int64, title, description, payload, providerToken, startParameter, currency string, prices *[]LabeledPrice, photoUrl string, photoSize, photoWidth, photoHeight int, needName, needPhoneNumber, needEmail, needShippingAddress, isFlexible bool) InvoiceConfig {
+// NewInvoice created a new Invoice request to the user.
+func NewInvoice(chatID int64, title, description, payload, providerToken, startParameter, currency string, prices *[]LabeledPrice) InvoiceConfig {
 	return InvoiceConfig{
-		BaseChat:            BaseChat{ChatID: chatID},
-		Title:               title,
-		Description:         description,
-		Payload:             payload,
-		ProviderToken:       providerToken,
-		StartParameter:      startParameter,
-		Currency:            currency,
-		Prices:              prices,
-		PhotoUrl:            photoUrl,
-		PhotoSize:           photoSize,
-		PhotoWidth:          photoWidth,
-		PhotoHeight:         photoHeight,
-		NeedName:            needName,
-		NeedPhoneNumber:     needPhoneNumber,
-		NeedEmail:           needEmail,
-		NeedShippingAddress: needShippingAddress,
-		IsFlexible:          isFlexible}
+		BaseChat:       BaseChat{ChatID: chatID},
+		Title:          title,
+		Description:    description,
+		Payload:        payload,
+		ProviderToken:  providerToken,
+		StartParameter: startParameter,
+		Currency:       currency,
+		Prices:         prices}
 }
diff --git a/types.go b/types.go
index eae0227..d84eb4c 100644
--- a/types.go
+++ b/types.go
@@ -652,7 +652,7 @@ type InputContactMessageContent struct {
 	LastName    string `json:"last_name"`
 }
 
-// Invoice contains information about invoice
+// Invoice contains basic information about an invoice.
 type Invoice struct {
 	Title          string `json:"title"`
 	Description    string `json:"description"`
@@ -661,11 +661,13 @@ type Invoice struct {
 	TotalAmount    int    `json:"total_amount"`
 }
 
+// LabeledPrice represents a portion of the price for goods or services.
 type LabeledPrice struct {
 	Label  string `json:"label"`
 	Amount int    `json:"amount"`
 }
 
+// ShippingAddress represents a shipping address.
 type ShippingAddress struct {
 	CountryCode string `json:"country_code"`
 	State       string `json:"state"`
@@ -675,6 +677,7 @@ type ShippingAddress struct {
 	PostCode    string `json:"post_code"`
 }
 
+// OrderInfo represents information about an order.
 type OrderInfo struct {
 	Name            string           `json:"name,omitempty"`
 	PhoneNumber     string           `json:"phone_number,omitempty"`
@@ -682,12 +685,14 @@ type OrderInfo struct {
 	ShippingAddress *ShippingAddress `json:"shipping_address,omitempty"`
 }
 
+// ShippingOption represents one shipping option.
 type ShippingOption struct {
 	ID     string          `json:"id"`
 	Title  string          `json:"title"`
 	Prices *[]LabeledPrice `json:"prices"`
 }
 
+// SuccessfulPayment contains basic information about a successful payment.
 type SuccessfulPayment struct {
 	Currency                string     `json:"currency"`
 	TotalAmount             int        `json:"total_amount"`
@@ -698,6 +703,7 @@ type SuccessfulPayment struct {
 	ProviderPaymentChargeID string     `json:"provider_payment_charge_id"`
 }
 
+// ShippingQuery contains information about an incoming shipping query.
 type ShippingQuery struct {
 	ID              string           `json:"id"`
 	From            *User            `json:"from"`
@@ -705,6 +711,7 @@ type ShippingQuery struct {
 	ShippingAddress *ShippingAddress `json:"shipping_address"`
 }
 
+// PreCheckoutQuery contains information about an incoming pre-checkout query.
 type PreCheckoutQuery struct {
 	ID               string     `json:"id"`
 	From             *User      `json:"from"`